To pay for and download music on iTunes, you must have an Apple ID. If you previously set up your Apple ID but didn't add a credit card payment method, you can add it now. Adding a credit card number to your account makes paying for iTunes purchases quick and easy. The steps you take to accomplish this task depend on whether you use an iOS device -- iPhone, iPad or iPod -- or a computer.

From an iOS Device

Step 1

Tap "Settings" on the home screen of your device. Scroll down the Settings menu and tap "iTunes and App Store" to access your Apple ID.

Step 2

Tap your Apple ID and wait for the pop-up menu to appear. Tap "View Apple ID" on the pop-up menu.

Step 3

Sign in to the iTunes Store by entering the password that matches your Apple ID and tap "OK."

Step 4

Tap "Payment Information" in the Account Settings page. Tap the type of credit card you wish to use for payment. For example, you may choose Visa, MasterCard, American Express or Discover.

Step 5

Enter the credit card number, security code, expiration date, billing address and your phone number. Tap "Done" when you are finished entering the information and the "Home" button to return to the home screen.

Step 6

Tap the "iTunes Store" icon and find a song you want to purchase. Tap the album art once to play a clip of the song. Tap the button with the price to activate the "Buy Song" button.

Step 7

Tap the "Buy Song" button. Enter your Apple ID password when prompted to authorize the purchase of the song.

From a Computer

Step 1

Open iTunes on your computer and click "Store." Click "Sign In" if you aren't already signed in to iTunes. Enter your Apple ID and password when prompted.

Step 2

Click "Store" followed by "View Account" to access your payment information. Enter your account password and click "View Account."

Step 3

Wait for the Account Information page to appear. Locate and click "Edit" next to "Payment Type." Choose the name of the credit card you wish to use for payment. Enter the rest of the information requested such as credit card number, security code, expiration date, billing address and your phone number.

Step 4

Click "Continue" to save the information you entered and return to the iTunes Store. You are now ready to purchase songs with your credit card.