When you have selected a photo, element, mat or text box on your page and choose to move it around, alignment guides may appear.
1. The green alignment guide will align your selected element to the page.
2. The pink alignment guide will show you alignment to other elements or photos on the page. In this example, the pink alignment guide is showing up that the center of the sun aligns with the center of the photos on the page.
3. The blue guide shows the edge of your page. This is just a notification for you.
*there are also keyboard shortcuts you may want to use.