You can add a description to each image on your poster that can be used to print out a layout map. A layout map shows you the area of each picture and puts the description in to the boxed area as shown above. This is great to use when you send someone a poster but don't want to have all the captions on the poster directly but you want your friends to know what the pictures are of if they don't already know.
To add a description you can right click on the photo and choose Description from the menu. Pressing CTRL+D will also open the description editor for the selected photo.