These are the instructions:

To create an ad, go to Yearbook Market and click on the box to create a yearbook ad.   

1.  Sign up with a username and password.

2.  Choose ¼ page, ½ page, or full-page ad. 

3.  Click Build.  

4.  Choose a template. 

5.  Click to use that theme.                                 

6.  Upload pictures and add text. 

Here is a tutorial which walks you through the steps if you need additional help creating the dedication page:

Dedication Ad Tutorial