I created a social network, better then my previous ones, I need someone who can make it better then what it is, so maybe if you want to join and help

www.internetdownloadzone.blogspot.com/

This should work.
Go to the Area/Appearance/Edit Theme/ CSS tab

Then add this code:

.ow_page_container {
background-color:#000000 !important;
background-image:none;
}