First, the image needs to be hosted somewhere. Meaning, uploaded to a webhost of some sort. If you don't have it hosted anywhere yet, you can use imageshack. I use them for almost all of the signatures I create.
http://imageshack.us
This is usually easiest to do if you have two browser windows going at once.
Go to the main page of the forum. At the top of the page, under the main forum banner, there is a medium blue task bar with several forum options (FAQ, Members List, Calendar, etc). You'll want to click on "User CP"...the very first option on the left. Once there, click on "Edit Signature" from the options listed on the left side. This will open a new page that looks a lot like posting a new thread, or posting a reply on the forum. Inside the white signature box, you are going to want to put the code for the image you want to use in your signature. If you already have the image hosted somewhere, simply put this code:
PHP:
[IMG]http://www.urlofimage.com[/IMG]
Obviously, replace the fake URL with the actual URL of the image you want to use.
Now, if the image is not hosted anywhere, and you want to use imageshack to host it, go to imageshack.us and browse for the image you want to use on your hard drive, then click upload. Once it is uploaded, it will give you several image codes to choose from. You can use a thumbnail version or a full sized version. I usually snag the code for "Hotlink for Forums 1" which you'll see below the preview picture of your image. Copy and paste that code into the white box in your signature editor.
Once the code is in place, click on "Save Signature" and you're done. Next time you reply to a post or start a thread, make sure the box before the option "Show Your Signature" underneath the submit button is checked, and it will show up in all posts and threads you make from this point on.
If this all gets too confusing for you, go ahead and PM me and I can help you take care of this. We'll get you all set up.
🙂
Mimi