Programmable keyboard with arduino.

Good to everyone, please have a question help me or give me a little guide I would appreciate it.
I have a game on the intern project computer, it consists of a series of stimuli shown on the screen. I must make a panel or keyboard which will consist of 7 buttons 3 for some questions a, b, c.
4 to react to stimuli and two knobs to rotate a sphere.
I will do the panel or they will give it to me to program it via USB port, in this case I don't know how to do it. I am really confused by what you found on the internet is not very complete.
thanks a help yes, before hand thanks for ignoring.