Who becomes president at the end of mocking jay?

President Coin- who was originally the president of District 13 and was set to become the new president of Panem at the end of Mockingjay. Commander Paylor-who became Panem's president in Mockingjay after Katniss Everdeen killed President Coin.

Where does Gale go after mockingjay??

Gale visits Katniss before Snow's death and gives her a sheath with one arrow to shoot at Snow. Katniss asks if it was his bomb that killed Prim. Gale isn't sure and tells her to shoot straight at Snow before he leaves. While Katniss can never be sure that it was Gale's trap that did it, she realizes she will never be able to look at him the same way again, and lets him walk away without a word. Gale later moves to District 2, where he secures a "fancy job" working for Panem's new government. Katniss finds herself relieved by this instead of feeling any longing or anger, as she herself believes that Gale will forget her and will soon be "kissing another pair of lips."

What Happend To District 13?

Back in the 'Dark Days' (The Dark Days is a term commonly used to describe the collapse of the first rebellion in Panem, which occurred 74 years before the first book) , District 13 initially led the rebellion against the Capitol. However, the Capitol took action against this, and informed all of the citizens in Panem that they had destroyed District 13 in penance for their uprising. However, it's revealed in Mockingjay that the Capitol did not in fact destroy District 13. They permitted them to live, in secret, underground, as long as they promised not to try and rebel again; however, they still told the citizens of Panem that it had been destroyed.

What happens in Mockingjay?

A lot happens. The big deal in the story is that the Rebels begin to use Katniss to get supporters for their cause. They put a bunch of makeup on her, put her in an outfit she finds out that was designed by Cinna and take her to different war zones to get footage to make propaganda commercials.

She isn't too happy about this but plays along, thinking that maybe she's going to get to fight finally. But she eventually realizes that District 13 is playing her just the same way that the Capitol did.

Eventually she agrees to be their 'Mockingjay' (a symbol of rebellion) if Prim get to keep buttercup (her cat) and if they will rescue Peeta for her. They do, but by the time she gets him back he has been driven crazy and made to think terrible things about Katniss, to the point that he gets violent every time he's around her.

So things progress, and after a lot of training she convinces them to let her go into the capitol. Peeta and Finnick go with her, and a few others. It's supposed to be a propaganda thing, more war movies, but their leader dies (Boggs) and Katniss ends up being put in charge.

At some point Finnick dies, too by lizard mutts. They keep moving on. Peeta isn't violent towards Katniss anymore but he's not sure how he feels about her. They start playing a game called 'real or not real' to help him decide whats true or not. For example, Katniss is a mutt = not real. They eventually get to the outside of President Snow's mansion. Katniss of course has every intention of killing him.
They find then that a bunch of children are being held outside the mansion and a bunch of medics are dropped in to help the injured.Katniss sees that one of the medics is her sister. Before she can do or say anything a parachute bombs are dropped and Prim dies.

When Katniss wakes up, she's in the mansion. She is told that they have won the war and she is going to symbolically execute Snow with one of her arrows. But she doesn't feel that is right.

She has a conversation with Snow in which she realizes that the President of the rebellion is just as bad as he is and, on top of that, is the one who ordered the bomb to be dropped that would kill Prim
As Katniss goes out to execute snow, she realizes how alike she and Haymitch are because she has decided what she will do. As she strings her arrow she doesn't strike Snow; instead, she shoots the new President (Coin)and kills her immediately.

She learns that her mother will stay in the Capitol and Gale will not be returning home either. Only she and Haymitch go back home. 

Katniss is severely depressed for a while. Then one day somebody arrives outside her door. It is Peeta. They begin a slow friendship, Peeta now over the effect of what the capitol did to him. The friendship becomes love, and eventually they make love. Peeta asks, "You love me. Real, or not real?" Katniss responds, "Real."

There is then a brief epilogue where it is revealed that after fifteen years Katniss and Peeta have two children, a boy and a girl. She reflects on the fact that her children play on a grassy field that they do not know contains hundreds of bodies. That's the end!

This is a very short version!

What happens in The Hunger Games?

It is set in future America. It is set in a family of Katniss, prim and the mother. Their father died when they were young in a coal mine explosion. There are annual Hunger Games- a game where 2 tributes are picked from each of the 12 districts to battle it out against the 24 other tributes to win. From district 12 (where it is set) a boy and a girl must be chosen. Primrose (prim) Everdeen is chosen alongside with Peeta Melark. Katniss Everdeen, prims sister, volunteered to take prims place. Peeta and Katniss are immediately sent of to the capitol to be trained  Haymitch, their coach has an idea for them to be 'lovebirds' so fans will like them and will sponsor them. Katniss has the nickname 'the girl on fire because on a live t.v. interview she wore a dress that caught fire when she spun around. She gained a lot of popularity which was helpful when it was time for the games to begin.

All 24 tributes were put out into a large dome and the games began. The contestants had to run to grab backpacks full of essentials to survive and weapons. Katniss grabs water purifiers, a coat, food, tools, weapons, and a sleeping bag. It seems that a lot of tributes are still alive after a few days, so the game makers decide something needs to be done. They set fire to the forest Katniss is hiding in . And she escapes, though she VERY BADLY burns her calf. She hides in a tree. Katniss pairs up with a young girl, Rue. They throw wasp nest (trackerjackers) on some of the tributes and kill Fox faceAnyway Katniss and rue go out to destroy some of the other tributes camps and while Katniss is gone for a second, rue gets stabbed by marvel (one of the tributes). Katniss dresses rue in a grave of flowers while rue slowly dies an excoriating painfull death. 

Katniss meets peeta. She finds that Peeta has been badly attacked by Cato and needs urgent medical help. They find a cave, and Katniss slowly nurses Peeta back to health. (They continue playing the lovebirds for the cameras and get many sponsors.) When it's just Katniss and peeta left, the announcer says the rules have changed, and only one can win.  As they are playing at being lovebirds, they trick the capitol into thinking they are so in love, that they would rather both die. They are about to eat poisonous berries and die together, when the capitol says they have both won!

What are propos?

Propaganda shots, more commonly known as propos, were the advertisements, messages, interviews, and footage from the rebel side (although the Capitol had a few propos as well) and were part of the Airtime Assault on the Capitol. Propos communicated messages to Panem's citizens, giving statements against the Capitol, and provided a rallying point of sorts for the rebel war effort.

One propo was used as a distraction during the rescuing of Peeta, Johanna, Annie Cresta and Enobaria from the Capitol. It featured Katniss revealing how she met Peeta and their exchange with the bread. It also showed Finnick Odair revealing all the secrets he had collected over the years about prominent people in the Capitol, including President Snow's serious offenses.

What happens to Peeta in Mockingjay?

In the third book, Peeta is held captive by President Snow and used against Katniss. During his time in Snows mansion , he was tortured and beaten, and hijacked using tracker jacker venom to distort his memories of Katniss. The Capitol interrogated him for answers he did not have and was tortured even more.