The $ _GET method for multiple things really helps a LOT
$ _GET checks for the end of a URL, example "page.php?____"
For example as I am posting this, it says "newthread.php?do=newthread&f=90"
[The action do = a new thread and then it has a &f so the f part = 90]
Here is a tutorial I made (Needs work) with comments about everywhere to guide you!
:: PHP pastebin - collaborative debugging tool
*I know its a bit..unorganized but I tried!