1) log in to QQ.
2) Click on the QQ space icon.
3) Enter the QQ space, click "Dress up", and then click "Dress up the mall".
4) In the navigation bar, under "Dressing Mall", click "Single Item".
5) After clicking on "Business Card", you will see many business card backgrounds, including free and exclusive for users of yellow diamonds.
6) Click to select the available business card background, and then click the "Save" button at the top right of the interface.