To add a contact to your address book using Yahoo! Messenger:

1. Click the "Add" icon located on the Yahoo! Messenger toolbar or click the "Contacts" menu and select "Add a contact."
2. Enter all the information you want to include.
3. Click the "Save & Close" button.

When you add a contact to your Messenger List, the contact is automatically added to your Yahoo! Address Book.

Please Note: From within Yahoo! Address Book, when you add a contact with the Add Contact form, you can add the contact to your Messenger List, too, by entering the person's Yahoo! ID in the text field provided and clicking the checkbox labeled "Add this person to my Messenger List."