Ok people, this is a new tutorial on showing you how to add a custom pic for your default background when you launch CS:S. First click on the folder Steam > Steamapps > yourname > CS:S > cstrike > Materials.
Once you are inside the Materials folder, create a new folder and name it "console".
Ok done, now it is time to go download a background picture. I download mine from www.fpsbanana.com. They have really good ones there.
Once you have downloaded your background, if you open the file it should be named background.vtf or something like that.
Now all you need to do is ADD this file INSIDE the "console" folder you have created earlier. And voila! You are done!!
I hope you enjoyed...