For you, seeing as you probably are a beginner, looking at the Tutorial board would be ideal. There you can find many tuts (tutorials) on creating your own head as well as making a matching set. If you fail to find the tutorial board try to use the nice little search feature we have at the top of the forum. Type in these exact words "Creating head texture new improoved." That should take you directly to the thread that will explain it all. If you have any questions feel free to ask me in pm. Good luck to you.
Edit: Also, when you have the time check out monobi's head texture tutorial. If your really pumped about making a good head texture that is one of the best tuts out there.