I need help with background maps

[GeorgeTheGasmaskCitizen]

Hello, I'm new to the HL2 Beta forum, though I've been messing around with modding on the beta leaknet engine for some time already.

Anyways, lets get straight to the point.
How do I make my mod load a map as a background map?

[Shift]

https://developer.valvesoftware.com/wiki/Menu_Background_Map

[GeorgeTheGasmaskCitizen]

Thank you!