Total noob - need help with gravity and colissions

Ok, so, I’m new to unity - came straight from GameMaker ← crappy 3D - and i need help figuring out how to get my character to collide with the terrain (so that he doesn’t keep falling out of the world). The tutorials have been pretty much useless with this because if your not using the same project, it makes no sense.
My character is sort of in .Obj format (he’s really a bunch of polygons in grouping so that he can be animated) but he IS one unified object.
Also, I can’t seem to get any sort of keybord input (what ever little experiments I’ve done in rudimentary code with ASCII keys doesn’t work)

Any and all help is appreciated

Have a look at the scripting reference and the manual. For collisions you need a collider on the object, for input search the scripting reference. It’s all in there.