well first find a image and then copy its URL, and then put this code in you sig on the profile

[code:1][/code:1]

it has to be uploaded somewhere.

you can upload it here on the forum, theres a topic for that, called signature testing (my sig is there too).

so upload it there, then click on the smaller version to get the full picture, right click the full picture and then go to properties (or whatever in you browser) and copy the url of the picture.

then do the above.