The Win7 built-in graphic software (MS Paint?) is not capable of anything. Most of us use Adobe Photoshop, or the free
Gimp. These programs can handle the different layers, different brushes, effects, fonts, vector graphics, etc. Of course, these programs much more complicated, but a lot of tutorials on the internet, on the youtube, which explain from the basics. If you are seriously thinking about creating skins, these programs must be used.