Bumpmaps give u a bumpmap look to u're textures - google it
they can be used with 512 texts, u need someone to make u bumpmap textures - u can not use regular texts for bumpmap, u can make em u're self, just look up on some bumpmap tut in the tut place of the forum
I think they do not work atm with tb 3.9, I might be mistaken, possibly they work if u turf of ray-tracing, ask at irc support