In this manual you'll find how to check performance problems, how to change needles, how to adjust the presser foot and needle bar, and all the other basic information you need to get started on your machine.
Sewusa.com also has a free guide online for threading the machine and needles.
A serger (sometimes called an overlocker) can help you make clean seams. But if the tensions are off on your machine, you may run in to scary problems.
I found this online tutorial from sewmccool.com to be comprehensive and easy-to-follow, with lots of pictures and descriptions for working on an overlocker.
You should definitely check it out to understand your white SuperLock 534 Serger a little more.