Welcome to the Board!
You'll find a lot of different uses for Excel, both personal and professional. It's got a myriad of uses, from simple check registers to statistical analysis and more. It's really up to what you want to do and how complex you want to get. Get ready to be frustrated at times, because it's a hugely complex program, but simplistic at the same time. Many users will never get past Excel as just digital graph paper, while some will go on to delve into it fully. That really depends on you. The most important thing is to have an open mind, because generally if you can think it, Excel can do it.
I stumbled into Excel as a job requirement many years ago and it literally shaped my career to where I'm now primarily an Excel developer.
As for resources there are lots of books out there, Bill Jelen (aka Mr. Excel) has several, as does John Walkenbach (
www.j-walk.com). There are also a lot of tutorials that a Google/Bing search will turn up.
The
Microsoft Template Gallery is a great resource and will (generally) give you good ideas about proper layout, design and functionality.
The best thing to do is just start working with it, and be open to asking questions - no matter how trivial or complicated they may seem to you, it's a good bet someone here can answer them.
HTH,