You need to donate $20 or more to get the donation privileges as listed from the thread
http://forums.justcommodores.com.au/site-feedback-site-problems/59978-donations-jc.html so dig a little deeper if you want a picture in your signature.
With any donation of $20 will not only give you a warm fuzzy feeling that you're helping the site but give you the following:
* 50meg in attachments.
* 1000 Private messages (PM's).
* Profile pictures can be a maximum of 300x300 pixels and up to 150kb in size.
* Avatar pictures can be a maximum of 200x100 pixels and up to 120kb in size.
* Signature images can be uploaded and be animated to your hearts content.