play stockfish

so I have been trying to play against stockfish but I cant find out how if I go on vs computer stockfish isn't there, like what?

You can't play against Stockfish here.

if I download stockfish it will just appear as a file but I cant find out how to actually use that file and play stockfish,(and yes, the third link is to download stockfish)

If you're using Windows just download Tarrasch from here. Comes with SF.

Be aware that when you "play Stockfish" over the UCI interface you actually play the GUI (Tarrasch in that case) and SF acts as consultant on the moves. I think GUI decides on the think time so you may get different playing strength with different GUIs.    

If you want it drop-dead simple, just download Lucas Chess. It has Stockfish preinstalled with different strength levels.

https://lucaschess.pythonanywhere.com/downloads