how to apply textures?

im doing thi walk trough, i took a template called wild house , took the wild house out and put my stuff in , but i cant put my textures in.

i want he floor to have a texture called cantera ( wich is packed )

i select the floor ( wich , i dont know looks black ) i press f , add the texture in the uv editor and i dont see it in textured mode or in game mode.

help !

edit mode ---- then ----- se;ect the vertice of the floor , go edit— normal — flip normal