Step 1: Open paint (or photoshop, if you can be bothered to pirate it). Step 2: Cut something out of a picture and paste it into paint. e.g. A background from a nice wallpaper. Step 3 [optional]: Cut a character out of a picture and paste it on top of the picture you previously pasted. (Bonus points if it's pre-cut with a transparent background.) Step 4 [optional]: Download some photoshop plug-ins to effortlessly add "special effects". Step 5: Write your name on it. Yes, it's really that easy. Here's an example:
*It's super effective! Paras fainted.* I couldn't be arsed making my own background and I got tired of my last one. Protip: Use photoshop, it lets you look all artistic and shit if you tweak the colors and contrast.