Start here for some basics
http://www.pspmod.com/forums/showthread.php?t=858 (PSP Greatest Hits?)
and read this before posting any other questions
http://www.pspmod.com/forums/showthread.php?t=739 (question about 2.0 updgrade)
It is important to read the sticky's and use the search button. A lot of people here and on any other forums on the net will insult you and belittle you (called flaming) for asking questions that have clearly been either answered in a sticky (link number two) or have been answered a bunch of times before (the search button will be of help here). Just trying to save you from having to read 15 posts from kids telling you to go f yourself and such. if you have specific questions after reading all the info in those two links you can PM (private message) me or post a new thread asking your question but make sure you include as much detail as possible when asking your question. Good luck to you!
EDIT: On the first link, do not update by following the link that says "to get 2.0 go here" because that link points to the sony page where the update is currently 2.5. Tripod... when you read this will you take a second or two and change that link to the 2.0 update on either PSP-hacks or pspupdates so people don't go to 2.5 and then screw themselves. Thanks in advance.