ok i downloaded bluetabs as one of my theams, were do i go to change the logo i have it but were do i insert it to make it my logo not nukemods.com ???

Ah would not leave that nukemods.com logo there 8) only kidding

If you right click on the logo & properties, it should give you something like this

yoursite/themes/yourtheme/images/logo

or

yoursite/themes/yourtheme/forums/images/logo

upload your image to either directory and rename to logo

Theres just one problem that might occur, your image might be a .gif .jpg or other, in that case you need to open your themes/header or theme.php file and search that for your logo.something and rename that to match yours etc..