The basics are:
W for going up and jumping
A for Left
S for going down (And to fall down faster)
D for right
F for throw (It actually does lots of damage)
Left click on the mouse for attacking/fighting

How to jump higher and faster:
Smash your W key while clicking the attack button

There is also a chat system:
Press enter to be able to chat and say something like "gg ez" after winning a round

(This game is endless so you can kill your friends as much time as you want)