Hi JustDeb,
I'm not going to disagree with any of the previous posts. But I will offer my take on this topic.
Music Theory can seem very confusing and intimidating - but it all makes perfect sense once you learn all the archaic jargon. People have been fascinated with music for many centuries, so the technical language of Music is ancient and foreign to our ears.
The Circle of Fifths is a useful tool for beginning to understand the relationship between different tones, the structure of chords, and also key signatures. Here is a Wikipedia article that offers some insight:
http://en.wikipedia.org/wiki/Circle_of_fifths
However, the article gets rather technical . . .
Here is a simpler take on the topic. The Circle of Fifths is a shortcut for helping to describe lots of technical details. It is a handy-dandy tool for transposing and for displaying the logic of the key signatures.
While the Wikipedia article itself might not be useful for you, check the links at the bottom to find some interesting sites.