Unity Character Customization

I am going to make a 3D fighting game.I am using Unity3D Engine and i am new to it.For my game i need a character..Some how i have find some 3D character with their .fbx and .tga and .obj file..I don't know what are these extension. I just import .fbx file in my unity.and now i can see my character on the interface.Now i want to customize it.like i want control it with my keybord.Like when i press some key it move forward,or when i press some button it hit a punch and some thing like that but How can i do it i don't whether i have write a script or any thing else.I am even not pretty sure that is it do able or not...SO any idea's or suggestion.plzzzz