Hi http://store.steampowered.com

It's quite simple, all you have to do is click on "subscribe" on the page:

http://store.steampowered.com

Once subscribed, open your Left 4 Dead 2 game and click on "ADD-ONS". The add-on will be downloaded automatically. You will have the option to activate or deactivate each add-on downloaded.

i got no clue how to use it, heck i got no clue how to use any mods

Hi http://store.steampowered.com

You have to do the same procedure as I described earlier with each add-on that you are interested. Click on "Subscribe" button on the respective add-on page and it will be downloaded automatically when you open the game.

When you hit the green SUBSCRIBE button, it downloads in L4D2 or any Workshop item is Steam. Then there should be a ADD-ON box. Click on that and it will take you to ALL DOWNLOADED ADD-ONS/Mods. Near each file is a checkbox. Once it is checked, it is in the game. This one is a re-texture so any Magnum you find out there, you find this weapon. Simple as
1) Hitting that BEAUTIFUL green button.
2) Checking if it's checked in the ADD-ONS folder
3) Find the Magnum.
Hopefully, this helps.

o

You pull the trigger and aim it at someone you don't like.

lol

use it in battle