First off you need a webhost for pictures, I use Photobucket. Then make a picture (.bmp, .jpg, .tif, .gif) you want to use in your sig. My GB badges and the current project pic of the three planes are two separate images. To grab the GB badge, right click on the badge you want and download it your computer, then add it and what ever else you want in the signature pic to your photobucket account and use the [img] tags for the pic you want.
To use the [img] tags, you must go into the update your profile. In the signature box add any text you want and to add the pic. The [img] tags will be addd to the text in the sig box and will look like this: [+img+]http://the addressofyourhost/youacct/thename_of_the_pic [/img+]. I added the + symbol or else it would try to find the non-existant pic I tried to point it to. take the + out.
To add an avatar, save a pic of yourself or what ever you want to use (like my Conan!) on your hard drive some where and use the browse button in the avatar section to go to that spot where you saved the pic, hit update. it will take a few minutes for it to appear.
Also be careful of the size of the image as there are supposedly limits for sig pics according to the sticky post near the top of the GB section!
go nuts dude!
...Hope this helps!