What do i do with .img and .sub files?

I googled these file types but the info i got was that there should be a .ccd file as well, but I don't have that...just a .img and a .sub file...how do I mount these files to a cd to run?

You can right click on the img file and open with your burning software.
Or select File->Open-> and locate the img file to burn

then what do i do with the .sub file? is it important?