Model file format

Hi! I''m pretty new to gameprogramming, and for practice I want to write a modelviewer for Q3- or HL-models. I read lot about OpenGL so I should be able get it on the screen, but I have no clue about the file format these Games use. On wotsit.org I found nothing so I want to ask you if you have any information about this stuff. Thanks in advance, Max PS: Please excuse my bad english