Hello I can’t add my credit card to my wallet, how can I do?

Have a look at the steps mentioned in this related article:

Set up Apple Pay - Apple Support

And your banking institution has to support Apple Pay:

Countries and regions that support Apple Pay - Apple Support

Open your Apple Wallet app. At the top of your screen, click on the + symbol. A list will appear. Select Debit or Credit Card and click the Continue button. This should bring you to a screen that will allow you to either scan your credit card or you can choose to enter in your information manually. I hope this helps.