Same way you wall paper a wall. It won't take all that much wear and tear by itself so coat with several layers of a clear protective like polyurethane. Comes in matte, satin or gloss. Let dry for at least a day in between coats to dry thoroughly.
https://www.pinterest.com/pin/502362533434842086/?nic=1 check that pin
Great idea from Em. You could also use a pretty fabric and mod podge it.