you have to take the first4 character of track name and add _lod so you get this,
trackname.jpg to trac_lod.jpg
trackmap will be a bmp file. tracknameTrack.bmp
lookin gtr2 folder @donnighton for screen dimensions
4don_lod.jpg : dimensions 800 x600 24 bits
4don_lod2.jpg : dimensions 800x400 24 bits
4donningtontrack.bmp : dimensions 142x85 24 bits
first one being the trck load picture,second being the moveable loading bar,3rd being the track map