BMI AND ASCAP collect the royalities and pay the copywrite owner.
There is a standard collection fee, usually 12% and 80% to the original copywrite owner. This means there may be
8% available for you. You will have to register with one of them when you publish the song. It will be assigned a barcode upc. Don't waste your time on cover songs for a profit. BMI /ASCAP will also be the one you will get a letter from the courts advising you to appear if you publish a song for sale. If your just doing cover songs for fun an not for profit, you'll be ok.