Find an e-commerce platform that is compatible as a partner with PayPal (see References). For example, E-Junkie, SoftSeller and DigiVendor are all pre-integrated with PayPal.
Go to the E-Junkie website (see Resources). Click on the option to register for an E-Junkie account at the top of screen. Follow the instructions and complete all of the needed information to create your account.
Set up a PayPal business account if you don't already have one. Go to the PayPal website and click on the option to sign up for a business account (see Resources). Enter your information in all of the required fields and click on the "Complete" button when you're finished.
Apply for the Website Payments Pro option located at the "Merchant Services" of your PayPal business account. Click on the option to sign up. You'll be notified if you're approved within 48 hours. Accept the pro billing agreement once you're approved.
Click on the "Profile" option from the top of your PayPal account. Click on the "API Access" option and then click on the "View or Change API Permissions" option. Select "Signature" for the type of API, and enter the API user name, robin_api1.19.5degs.com. Select "Direct Payment" and "Express Checkout" for your API Access, and once you're finished go back to log into your E-Junkie account.
Go to the "Seller Admin" option on your account, and then click on the "Edit Payment Preferences" option. Click on the box next to the "PayPal Website Payments Pro" option. You will now to be able successfully upload your music in MP3 format to the E-Junkie website by going to the "Upload Product" screen. Once you've added your music you'll need to click on the option to create "Add to Cart" and "View Cart" button codes to be placed on the website where you want your music to be sold.