You can edit your photo in the "Print options" page, just before placing them in your basket.
To crop your photo, click on the small thumbnail or click "Crop this photo" next to it. You'll see your photo in a bigger version, and an orange frame. Anything within this orange frame will be how your print is printed, anything outside of the orange frame will be cropped. To cut out a part of your photo, simply click and drag the corners of the frame. Then click inside the orange box drag it to the sides.
You can also choose to crop your photo in a landscape or portrait format. The option that fits your photo best will automatically be selected, but if you wish to change this simply tick the other option or rotate your photo.
My photo is cropped, but I don't want it to be
If you see that your whole photo doesn't fit in the orange frame, it means that the photo has a different aspect ratio from the chosen print size. To get the whole photo printed, try to change the print size to find a size that fits your photo better.
If you don't want to change the print size, use the "Shrink to fit" feature instead. This will include the whole photo, but you will have white edges on the side of the print. After you've ticked "Shrink to fit" you'll see how the photo will be printed using this feature.
Important note: To avoid cropping your photos you can use a photo editing software that allows you to crop your photo to the precise dimensions you require for the selected print size. However, please try not to have important detail on the edge of the print, as 2-3mm could be cropped around the edge (manufacturing bleed area).