Okay, it's fairly easy, for someone that's used linux for a while. First of all, you'll want to set up your computer so that the browser opens at start. The exact setup depends on a lot of things, namely your browser, your desktop (assuming gnome/kde here). All you should have to do with most browsers is get them up and running with the page you want as the default (home) page. Then, each time the browser opens, you'll get that page. The harder part (not that hard), is getting your browser to open up each time X starts.
For that, you'll need to ask how to open a browser automatically with whatever desktop you're using. In other words, details about your desktop and browser you're using would be nice.