Background of STL have an music bg/known as gamestartup music any way just put it at the correct folder.
OK..You don't know.. If you don't have materials/console create the folder 1.Create a folder(Materials) 2.Click inside and do the same(1.)but name it console 3.Drag the background.vtf and put it in.
There 6basic steps if you don't know just pay me $120 Singapore $$$
Create by Zube1337(using M3D plug-in from MilkShape3D)
Thanks to these programes:
Adobe Photoshop with DDS & VTF plugins MilkShape3D(MS3D) with M3D plugins CSS test view of the image