example pack here http://gamebanana.com/css/guis/27896
https://developer.valvesoftware.com/wiki/Menu_Background_Map
If you're wondering how to get a different background-wallpaper (and/or background map)
for (almost) each game start. Like in HL2 game.
Cvar
The game has a cvar that remembers where you left off the last chapter.
"sv_unlockedchapters" = "1" archive - Highest unlocked game chapter.This cvar will not change in any phase of the (Cs:s) game.
Chapters
"chapters" { "1" "background01" "2" "background02" "3" "background03" "4" "byanyothername" }The first parameter is the chapter number. The second parameter is the name of the background.
Or you end up in this, missing texture

Background texture
The game is loading the background texture from here, ...cstrike/materials/console/
background01.vmt
background01_widescreen.vmt
background02.vmt
background02_widescreen.vmt
background03.vmt
background03_widescreen.vmt
byanyothername.vmt
byanyothername_widescreen.vmt
(Which may be located somewhere else other than here in the same folder)
"UnlitGeneric" { // Original shader: BaseTimesVertexColorAlphaBlendNoOverbright // Uncomment this if you add an alpha channel to the base texture // "$translucent" 1 "$basetexture" "dev/dev_signflammable01a" // Example "$vertexcolor" 1 "$no_fullbright" 1 "$ignorez" 1 }
This far, different background images should be in action.
Background maps
// load the base configuration //exec default.cfg r_decal_cullsize 1
// Setup custom controller exec joystick.cfg
// run a user script file if present exec autoexec.cfg
// // stuff command line statements // stuffcmds
// display the startup level startupmenu
There are a few things that prevent the background maps working.
Adding this cvar in launch options change the game in singleplayer mode.
+maxplayers 1

Finally, what I have already mentioned a moment ago.
You need the background maps that is named after the "chapters".
The maps must be located at this path ...cstrike/maps/
example maps to above "chapters"
background01.bsp
background02.bsp
background03.bsp
byanyothername.bsp