how do I complete AppleCare setup and link to my Apple ID

I lost my credit card and closed that account. I had to get a new one but did not change my new card number in Apple ID. I received an email from AppleCare+ that I had to complete AppleCare+ setup and link it with Apple ID. I changed the charge card number to my new card, but I do not know how to link AppleCare and my Apple ID. Since I don't have much technical experience, I need to find out exactly how to do it.