The address-card icon appears next to names of people who are in your Yahoo! Contacts folder. How do you add people to your Contacts folder? Here are two ways:

• Click your Contacts folder in the folder list along the left of your Yahoo! Mail page, and then click (along the top) on the "New Contact" button.
• Or, open a message from a person you'd like to add to your Contacts folder, and click the "+" button next to their name.