New to Gmod, can someone teach me how to add PHX and addons?

I used to play this a year ago when I had a laptop but it broke so I had my stupid desktop that didnt run Gmod now I made it faster and Gmod works! Back then i was pro at addons now i have lost my skillz =[ so I wanted to know if someone could help me from the point I click download I would be very happy if you did.

here’s a guide for phx:
http://www.facepunch.com/showthread.php?t=688324
and for addons:
and here’s one for addons:
http://www.wikihow.com/Add-Stools-and-Addons-to-Garry’s-Mod

Have fun :smiley:

Thank you!