Ok Cowgurl.
Go you your "UserCP", then "edit options" then scroll to the bottom of the page and find the section Miscellaneous Options. On the drop down bar there, change from Basic to Enhanced.
<--This will alow you to have more options like smilies, color options, and the photo icon. Then go to edit sig and insert the picture with the picture Icon. (The sig must be size 400x200 or smaller) You can host any picture from you computer on www.Imageshack.us.