Because you have good intentions, I dont think I have the heart to flame you =P Plus everyone has to start somewhere when it comes to motors. Not everyone realizes that on here but oh well. anyways:
download the Factory Service Manual (FSM). For anything Factory related, IE replacing factory parts, its just about all you need. As a newb, and being 26, (meaning you have common sense) try and use the search function as much as possible before making posts on zilvia with questions. Otherwise you just get flamed and never get answers. which is not what you want.
This crowd can be really bitchy when it comes to previously asked questions, especially the ones that are asked every week. But theres some good threads and knowledgable members on these forums so stick around and try to figure out how things work.
Search for the 240SX FSM, its on here, or on google somewhere.
www.zeroyon.com might also have it.
Goodluck.