Haha yeah magic is sometimes the only way!
Really though you're going to need Adobe Photoshop. If you don't have around $700 to buy it, and don't want to be hunted by the FBI cause you violated the non-active SOPA. Then I suggest you download GIMP
(GNU Image Manipulation Program) which is very similar to Photoshop with a huge bonus - it's free! Assuming you have no knowledge of using graphics design software you're going to need a few tutorials to get started and learn the features. There's loads of sites by searching google but there's lots of basic forum graphics tuts, like avatar and signatures, right here
Follow those tutorials and use a little creativity and you should have a sig. Or if you need anymore help/explanations then just ask but the topic that Moonshield provided has everything you need for starting GFX.