I'm kind of a newb to JK2Radiant, and keep hearing about this worldspawn thing, and it's uses, but what the heck is it, and how do I acess it, or use it?

Every map has exactly ONE worldspawn. It is an entity. So if you'll look under your entities your see it and what it can be used for. Such as:

key --> message
value --> Text to print during connection, such as the level name

key --> music
value --> the path to a .mp3 file, such as music/musicname.mp3

You can also affect the gravity of your level with the worldspawn too.