I took a quick look. It's just c and opengl, so you should be able to load a model and display it like the tutorial for loading objects. You should be working through the tutorials for ArTool and probably ask your teacher for help if you can't understand it. ArtTool looks like it may have model loaders, are you sure it doesn't? If there is a forum for it, that's the first place you should go to ask questions, rather than a general forum like this one. Otherwise it uses Glut, so just find some Glut tutorials on opengl if you can't understand the tutorials from ArtTool. You should start by making triangles and quads and such before working on a model loader. NeHe has some opengl tutorials. From the looks of it, though, I would guess they already have a model loader set up.