coldet

I was wondering how would i exactly do colission detection?I saw something at www.fluidstudios.com demo is great but code is to my as of yet almost nonunderstandable and doc is also unclear.I was wondering for detection using ellipsoids or at least boxes is there any clear document and code about this because just spheres are not good for my game.Any code?Did you try this ever?How do you do it?Thanks all!!!!!!Also how do you control position of your models i.e. i have an alien and he walks, when he falls would i change his postion with gltranslate or else? Real life is in infinite number of pixels x*y however i use computer finite 1600*1200 Ripper