Before you place your prints order, you can preview your images to confirm any auto-cropping that may be done to fit the correct size print. If you are in your Photo Cart, click the link for Glossy or Matte Print(s) to go to the Choose Sizes and Quantities Page.
Click the Preview/Crop link under the image thumbnail, then click the size of the print for the image you'd like to preview. You can click and drag to change how the image is cropped, zoom in or out, or rotate your image here. Click Apply Crop after you've made edits to your photo. Click Cancel if you have no changes to make.
For more information about auto-cropping, see Why is some of the image missing from my print?