ok try this for changing the background to a pic
open ththemes/fisubsilvershadow/style/style.css and find this
Code:
.bodyline {border:0px solid #345487}
(It won't be exactly the same but it will help you out)
and change it to
Code:
.bodyline {background-image: themes/fisubsilvershadow/images/back.jpg;border:0px solid #345487}
It is just a guess because my testsite is down so I can't test it first