Hi,
I’m not the one to give you any sort of detailed response–very new at this but given no one else has… There are a variety of threads if you do a general search on this site for “normal maps”. Specifically though, in MotionBuilder you need a normal map image of a texture rather than an RGB image to use the bump map shader that’s included in version 5. The normal map you need can be generated from photoshop or gimp and is a greyscale transformation of the RGB image that uses lightness/darkness in some way to give input to the bumpmap shader, which in turn gives the appearance of geometry to a texture without it actually being there.
It appears this is a simplified version, and not as good as the other type of normal map application (ATI’s normalmapper, ORB) These take in a low poly and a high poly version of a model and are able to provide the low poly with the appearance of much greater detail without actually increasing the polycount.
I apologize for any errors and simplifications.
JRH