Adding thumbnails to Photogallery

Hi there. I did kirupa’s “Adding thumbnails to Photogallery” tutorial.
It’s a great tutorial.

I have troubles placing the “thumbnailMC” where I want in my .fla
In the tutorial, it is written : “make sure its X position is on 22, and its Y position is on 289”… Why? Where can I change these values?..

Thank u so much for answering