A color wheel won't help you very much unless you know how to use it. There are lots of websites, classes and books these days that can teach you about color theory...many specifically for quilters. It's great fun, not complicated at all, and can make color use and selection so much easier.
BellaOnline has a good series on color theory and they start right out with how to use the color wheel (but don't stop there!).
http://www.bellaonline.com/articles/art4672.asp