How to Add Custom Music to Arma 3 Scenario [Gatecrasher]

This tutorial was mainly directed to the Gatecrasher Milsim Unit but anyone is welcome to view the video.
NOTE: If you want to make an .ext or .sqf file you need to create a .txt file with right click in your scenario folder and enable view file extensions under view at the top tool bar of the file explorer. Then edit the name of the .txt file and change the .txt to .sqf or .ext and press ok on the prompt that shows when you press enter.
Credit to PickinThatBanjo for the description.ext and general tutorial I'm just passing this information onto my own arma 3 unit because most of them are stupid. Mainly Lad.