When viewing a yearbook, look for Who's in this book? on the left to see everyone tagged in the yearbook.
The names listed include members identified using the text within the book, plus any members who have been tagged by other members. The numbers below each name reflect the page(s) that person can be found on—simply click on a number to go directly to that page of the yearbook.
Keep in mind that only registered Classmates.com members will be shown on the list.