The first step to texturing a model is learning to create a proper UV Map; I use [url=http://www.unwrap3d.com ]
Ultimate Unwrap 3D[/url], which has a few starter tutorials on their site. UV Mapping is difficult to learn at first, but with time it will get easier (depending on the complexity of the model) as you develop your own process/pipeline.
Another good UV Mapping program is LithUnwrap; here is a
link that contains tutorials, as well as a link to download the program itself.
As far as using GameSpace's native UV Mapper; Drew Clark has put together an outstanding
mini-course for under $30. Also, if you haven't found it yet, there is a free introduction to the GameSpace UV Mapper
here.
Next you'll need to know how to use a paint program such as Paint Shop Pro, Photoshop, The GIMP, etc. Here's a
small list with links to a few programs to get you started.
Texturing your 3D creation can seem to be a pain at first, but with time you'll get better.
-Keith