Well sometimes, people have problems to add signatures/images in forums so I’ll explain you the different codes.
First at all you have to upload your signature, I use imageshack or my blog, you can use other programs or webs.
If you have the link of you signature/image you will able to add it in forums.
Forums can use HTML code or BBcode:
If it use HTML you’ll write: img src=”your image’s url”> add < before img
If use BBcode: [IMG]your image’s url[/IMG]