To resize your layout or an element, open it in Photoshop or PSE.
Duplicate your file by selecting Image | Duplicate.
Select the Crop tool, then in the Options bar across the top of the editing window, type in the size you want to overlay to become (6 in by 6 in or 8 in by 8 in.) at 300 ppi (for print quality.)
Click and drag around the outside of the overlay.
When you release the mouse click on the green check to confirm the crop. Your file is resized.