Optional video tutorial for installing SuperBLT, BeardLib, and mod_overrides mods: https://youtu.be/rin_sjSJIkg

After downloading the mod, use a program such as 7zip or WinRAR to extract the main folder of the mod.
Move the main folder of the mod to assets/mod_overrides. The assets folder is supposed to be in your game's installation folder (don't know where that is? click here). Create the folder if necessary

How to install:
After installing the zip archive
follow this link and download the mod
https://modworkshop.net/mod/17160
The downloaded mod needs to be transferred to Payday2/mods
backgrounds in Menu Backgrounds/Assets