Well, you can call magick "Black", "white", "Green",..etc. but there are a lot of people (including myself) that view magick that has no color, people that invision magick with color, do so because it helps them visualize better.
If you want to join read through the covens and find one that best suites your needs. As you are a beginner, I suggest you read the "Bascis", which you can read in some books, in the "Article" section of this site, or in some of the "Forums".
Now, not every book, article, or forums will be truthful, there are lots of members that come on here to either spam or role-play. So read, but also keep in mind, if it feels to good to be true, it probably is.