Psx rom question

I just downloaded a psx game from the main site and it contained 3 files.
A .img file a .ccd file and a .sub file. What are those files and how can I make the game work????

What are you using to play the game?If you're using ePSXe, then any one of those files will play the game.

I'm trying to make it run on my psp but it can't read any of those files.

you can't directly play them on a PSP, they need converting. Check the tutorials section.

Would all 3 need conversion or only 1?

It's actually only one of them that are the image file, the others are meta data about the image file which you don't really need unless you're burning. Any decent converter should show you which files it need you to select.

Convert the .img file.