How to play music through mic?

[👅 f r e a k y c y r u s 👅]

Ive seen a lot of people do this, and im wondering how to do it without having to have outside sounds or my voice coming through.
Basically, I want the music played but not my voice or outside noises like my dog or something. I use Windows 7 btw, anyone know how to?
Also, I dont want any programs or something for it I have to download, just so I have my computer's sounds playing like a youtube video open.

[LilGaryComeHome]

https://www.youtube.com/watch?v=TmG54AXfVvY

[Baston]

Hahaha I saw a porn site in his research bar for like 0.1 seconds lol