How can I update my Mac OS X 2.0 web browser?

My girlfriend gave me this 2001 Max OS X with the green monitor and all of that stuff. I'm trying to go online but sites are too advanced for my current Internet Explorer 5.2.3 browser, so everything sucks. I am unable to download any current 2011 browser because Explorer cant read the Firefox sites or Apple sites and I need this fossil for college! Help!