You need to edit your signature. To do this, click on Profile under where it says New Topic and Reply. Click submit when it shows your name and password. Then when you're editing your profile, fill in what you want to where it says Signature.

To include your signature in posts, check the box where it says Show Signature under the message box where you type your post.

To add a pic, it should be on a website like www.webshots.com Right click on the picture and choose Properties. Highlight the address you see, right click, and choose copy. Then come to where you edit your signature and put the following:
[img] (right click and paste address here) [/img] with no spaces.

We can help if you have any more questions. Sorry if I didn't explain it too well.