Isn't this music here? This is a link from the Terror Radius addon page.
https://drive.google.com/file/d/1gHL6q2oVJjzULv2KvtV0jQHUbgTevFJp/view

where do i put it once its downloaded?

You should put "dbd_terrorradius" folder in your Garry's Mod folder, so it will look like this:
"<Garry's Mod Directory>\garrysmod\sound\dbd_terrorradius\custom\<Music files here>".
If there's no "sound" folder yet, create it.

i wish u made a video of this would be easier

Well, it's just about putting folder in another folder, so.

im a lil stupid

No worries. Where did we stop?
If you have already downloaded the archive, you can open it and find inside the folder I was talking about. Then in Steam you need to go to the local game files (right-clicking the Garry's Mod in your library, selecting "Properties", then "Local Files" and then there's button "Browse") and move the folder from the archive to the path specified above.

i went to garrys mod then i searched sound opened it and dropped the folder in there

So, does the ptb music work now? I think it's everything needed for it to work. If you don't need some other ptb music, you can delete unnecessary .wav files from that folder (or rename them).

i deleted it from my folder cause i did not notice a difference im trying again in the morning

and ive been moving heavy flat things of metal off my neighbors truck srry for taking so long