Previews are inside.
It includes the official maps(except for de_dust2 since it's the original):
Plus XBlah's Map:
Go to C:\Program Files\Steam\steamapps\SourceMods\cspromod\materials\console and extract the VTF, of the map you like most, and name it background01.vtf replacing the old one(remember to backup)
This(except for the CSP logo and the maps) was remade by me.It was my ideia to replicate the original CSP background, but with other maps than dust2.Hope you guys like it!