Hi LiLisLovelys, and Welcome!
This is a great place to ask questions, as everyone here is so friendly and helpful.
I have a simple serger, so my knowledge is based on that.
Basically, a serger sews, trims, and finishes the seam in one step. Have you ever sewed something on a regular machine and then have the edges of the seam fray? A serger keeps that from happening. If you look at the seams of a Tee shirt, those are serged seams. Sergers go incredibly fast, and stitch around 1500 stitches per minute. You can do different types of seams with a serger. The most common are the 3 thread overlock and the 4 thread overlock. Those would be the Tee shirt seams, the difference being if just one needle is used or both. Then there are rolled hems, flat lock seams, blind hems, and probably a whole lot more.
The hardest part of a serger is learning how to thread it. It looks really complicated, but it isn't. What you need to remember is that there is a certain order to threading it, and no matter what, it won't work if you thread it out of order. When I got my serger, I watched a video on how to thread it, and then did it over and over and over until I could do it without thinking. I also took an ultra fine marker and marked the order of the threading on the machine itself.
I bought Nancy Zieman's book Serge With Confidence, and that was a huge help to me. You should be able to get it at the library.
If you don't have a manual for your machine, get one. Do a google search and then order it from the internet. Then you just experiment. You will probably break a few needles and say a few colorful words, but in the end you will love it. Start with simple, quick projects, and build from there. And when you get stuck, just ask here. Even if we don't have the answer, we can certainly sympathize with you!
Good Luck, and let us know how it goes!