You don't "combine cube and meshes" a cube contains a mesh (the mesh is what makes up the cube ;)).
I would check out this post:
And also, have a look at unity's FPS and platformer tutorials, they are very detailed and walk you through a lot of core elements of unity.
Also, it sounds like you need to learn a bit more about the 3d modelling side of things (coming from the quote at the start of this answer). I would suggest http://3dbuzz.com for this. Altho, if you type "3dsmax tutorial" or "maya tutorial" in google, you will get some good results. Also, it depends what 3d package you have, if you don't. Do some research on the ones available and take your pick.
Altho you don't realise it, you have summarised many questions into 1, unanswerable, vague question. Once you learn more, you will come across specific questions that people can directly answer to help you. You have to help yourself in the meantime.
@DaveA Syclamoth actually said "I can't really answer the question" ;)
Technically, neither can i. But i have attempted to point him in the right direction so that he can answer his questions himself.
answered Oct 14 '11 at 10:45 AM