I still have all code if anyone wants to give the RRFN a go. RRFN.com is take. Red river farm network or something like that.
You know HTML, that is a start. A base to build from. You know forms then? The difference between POST and GET? HTTP and how variables are passed? If you know HTML then you should read and get to understand the RFC for HTTP.
http://www.faqs.org/rfcs/rfc2616.html This explains the http protocol and it's iner workings. Since html is the major base for all web pages it is good to under stand how it works inside and out. How you might be able to lets say extend the uses a page might have. Instead of CSS if you want to hack I recomend javascript and vb script.
http://webmonkey.wired.com/webmonkey/javascript/tutorials/tutorial1.html http://www.functionx.com/vbscript/Lesson01.htm Read these lite lessons on webmonkey
http://webmonkey.wired.com/webmonkey/backend/protocols/index.html That should give you a good base to ask the questions you want to ask that you do not yet know you have. As you learn you will have new questions.