Open VTFEdit, and press Import.
(Look at picture number 1)
Step 2
Find the picture you want to have. Select it and open it.
(Look at picture number 2)
Step 3
Press Save As... and put the picture into C:\Program Files/Valve/Steam/SteamApps/your-accountname/counter-strike source/cstrike/materials/console and rename the picture to: background01 and save it!
(Look at picture number 3)
Step 4
Open CSS and enjoy your new own background!
(Look at picture number 4)
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Do you want to uninstall the background, just go to C:\Program Files/Valve/Steam/SteamApps/your-accountname/counter-strike source/cstrike/materials/console and delete background01.vtf
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Hope this tutorial did help! (:
Thanks to:
My cat,
The photographer (myself)
And the many tutorials on the internet!