I want to add credit card in QB banking pay. let me know the procedure?

It's great to see you here in the Community, @srilekha-deviset. I can walk you through how to link your credit card account.
 

To link your credit card account, you can follow the steps below:
 

1. Go to the Banking or Transactions menu and choose the Banking tab.
2. If this is your first time connecting, select Connect account. If you've already created an account, you can choose Add account or Link account.
3. Look for your bank and click Continue. Then sign into your bank by entering your banking username and password. 
4. Follow the onscreen steps to connect. Your bank may require additional security checks. It may take a few minutes to connect.
5. Choose any accounts you want to connect. Then choose the matching account type from your chart of accounts in QuickBooks.
6. After setting up the needed details, select Connect.
    

For a detailed steps, you can click this article: Connect bank and credit card accounts to QuickBooks Online.
 

I've also added this article if you can't find your credit card account: Find your bank or credit card account when you connect to online banking. 
 

Please let me know if you're referring to something else or if you have any additional information in the comments section. I'd be delighted to assist you. Have a fantastic day and stay safe!