If you already have birthdays and anniversaries in your Yahoo! Address Book, you can add them to your Yahoo! Calendar by doing the following:

1. In your Yahoo! Address Book, click the person's name whose birthday or anniversary you want to add to the calendar.
2. On the resulting Contact Detail screen, you should see the birthday or anniversary date listed.
3. Click the "Add to My Calendar" link next to the birthday or anniversary date.
4. Your Yahoo! Calendar will appear in a new browser window with the birthday or anniversary added.

If you don't already have the birthday or anniversary in your Address Book, you'll need to add it and then follow the above process to duplicate it in your calendar.