I need to add my credit card for my payments.how?

Hi June- Welcome to King Care! To change your payment details please follow these steps: 

- Tap Settings > iTunes & App Store.Tap your Apple ID, then tap View Apple ID.

- You might need to sign in.

- Tap Payment Information.

- Change or remove your information.

For full instructions please visit: https://support.apple.com/en-us/HT201266 

Let me know how you get on :-)