NOTE: I DID NOT MAKE THIS. I TAKE NO CREDIT FOR THIS EXCEPT FOR CHANGING THE COLORS AND SAVING THEM AS .VTFS
To install drag all .vtfs into c:\programfiles\steam\steamapps\name here\counter-strikesource\cstrike\materials\console\
To use a different color, delete or move the background01.vtf some where else. Then rename the color you want to background01.vtf, i.e. red.vtf to background.vtf.
Sorry for the two uploads, file was to big to upload it all.
Screenshots:(Quality maybe reduced due to imageshack.)