Any one of our templates will get you started. You can replace the backgrounds, colours, text, fonts - everything. Use one as a guide to help you correctly position your content on the various box panels to ensure a proper fit.
There are no rules when it comes to box design. Some choose to mimic their card design on the front and back of the box, whereas others design their box with complimentary content and artwork. Businesses tend to use the box to convey further details and contact information that they didn't feel was appropriate for the card backs themselves.
Try a few designs if you like and add them all to your shopping cart. This will give you the option to review them all and choose the one you like best. Simply delete the ones you don't want before checking out.