To re-size a photo:
Right-click on the photo,
Select "edit"
Select "Image"
Select "Stretch/Skew"
now decide on the percentage reduction in the horizontal and vertical axes (make each the same to preserve aspect-ratio of image), type the numbers in and click the "OK" box
Save the image (either as the previous name or with a different name if you wish to keep the original image)...that's it, your photo is now re-sized!