Go to "Edit Signature"
Scroll down to "Edit Signature"
To add a picture, You must have the URL
Must include [Img][/img] Tags
If you do not know the URL of the image you want you can always right-click and "Copy Image Location"
You can also type into your signature!
Need Ideas for a signature?
Many users will you a signature called a Userbar
Userbars.com - The original userbar site with thousands of free userbars, forum signatures, photoshop tutorials, animator, userbar maker and more!
I hope this helps!
Make sure you scroll all the way down the page and press "Save Signature"