If you want to make signatures you're going to need a program such as photoshop. Photoshop tends to cost quite a bit so I would suggest on getting a program such as gimp or paint. Just go to google and search gimp. Or just go to paint.net
If you have Adobe Photoshop, then you should follow some tutorials to learn the basics of Sig making.
Good tutorials can be found at Gamerenders.com.
Renders to be used in Sigs can be found at Planetrenders.net.
If you are stuck on anything, feel free to PM me or any other member.