Metro supplementary card can be opened through the following steps:

1. After receiving the credit card, you can bring your valid ID, credit card and password letter to the counter of the local ICBC branch to open it. Card.

2. Enter the official website of ICBC, click "Credit Card", and then select "Apply for Credit Card Online".

3. After filling in the application form and submitting the information, the bank will review the filled in information and send the credit card.

Please note that the above steps are answers to the question of how to open a Metro supplementary card. They only represent the general handling methods. The specific operations may differ depending on the specific situation. It is recommended to consult in detail before opening the card. Metro customer service or ICBC customer service.