you need to texture with game purposes or only for some renders?
it changes a lot what you have to do
btw, you have to understand first how uvspaces works, they "say" how a texture will be painted to a face.
The uv mapping tools in truespace are locate on the left bottom menu bar, one of the last right icons, the uvmaps icons have some shapes (plae/cube/sphere/cilinder mainly) with white/blue chess. make some trials with this commands to see how they change the way textures are applied.
To apply textures click on the material editor, right click on the little color icon in the new window (or click on the color editor in the left menu bar), choose "caligari" as color and you will have a little window with the violet caligari texture and a button with the name of the texture.
click this button and you will be able to choose your own textures.
Remember that you can apply uv spaces and textures not only to the whole object but event to single faces and group of faces...just make a selection before applying uvspaces or textures.
Once you get more expert you may desire to use the lithunwrap to apply the uvspaces.
Make a little research in this forum with lithunwrap as keyword, you will get posts with useful links for this tool.
there are two main ways to apply textures:
"splitting" the object in logical units that will have the same texture and the same (almost) uvspace , go to
www.xwaupgrade.com here there is an useful tutorial about this way of texturing. It grants you good results but it requires an higher number of textures...and this is no good for 3dengines

, so use it only with simple models with a low numbers of units (and preferable with big units almost flat)
the second way is to use as said lithunwrap that lets you to reduce the number of textures a fighter require.
remember that freespace2 wants 256x256 or 128x128 textures in 256colorspcx format when truespace works with bitmaps.
cya