IRON MAN!

Also known as Tony Stark. This guy was young, rich and handsome and seemed to have everything he could ever want until one day there was an explosion which sent a piece of metal flying into Mr Stark's heart. This created a fatal disease in his body but luckily for him he had enough resources to create a device which helped keep him healthy and this was placed on his chest. Since he was already technically suited with this thing on his chest, he decided to create an Iron armor, which allows him to fly and shoot blasts out his hands, the suit is also bulletproof which protects Iron man. This superhero is also apart of the Avengers.

CAPTAIN AMERICA!

Steve Rodgers is his real name. Steve applied for the army more than one can count but still he never got accepted due to the fact of how small and weak he was. One day a doctor noticed Steve and saw how eager he was to sign up and be accepted. So he injected this weak, small Steve Rodgers with the Super-Soldier Serum. A serum which made one grow tall, strong and powerful. Now Steve was faster and stronger than any other man in the Army. With his Indestructible shield, excellent military knowledge and a strong belief in doing what's right he can't be stopped and serves his country whenever they are in need. Captain America was also the first avenger. 

THOR! aka The Mighty Thor

Thor's home planet is Asgard, his step brother is Loki which is also his enemy. 
Thor was too proud to be the king of Norse gods so he father Odin sent him to earth as punishment and told him to live as a normal human and until he learned how to be humble he would have to stay among the human race. As an even worse punishment king Odin erased Thor's memory, so he was living on earth believing his name was Donald Blake and he was putting himself through medical school. After a while King Odin realised how mature his son had grown so he returned Thor's memory and even gave him the Mighty Mjolnir, the mighty hammer. This allows Thor to call down lightning and wind from skies above. Since Thor now had something he could use to fight crime he decided to stay on Earth and fight evil.

SUPERMAN!

Superman is from Krypton.
His weakness is Kryptonite.
He has super vision, super hearing, heat vision, freeze breath, flying. These powers are all solar fueled. So to regenerate his powers superman would fly above the clouds and be charged by the sun.
His villians are Lex Luthor and General Zodd.
By day he is known as Clark Kent and his girlfriend is Lois Lane.
Clark was sent to earth from krypton in a space pod, he landed on a farm in Smallville and he was adopted by the owners of the land. 
Superman wears a red cape and red boots. He has the S on his chest which stands for Superman and it was also a symbol of hope back on Krypton.