Looks like they just braied her hair.
While your hair is wet, do maybe 3 or 4 braids, wait for your hair to dry, take them out and put hairspray, gel, or mousse to hold the wave.
OR
If your hair is dry already and you don't feel like washing it again, braid the hair the same as the other way, and then use a straightner and straighten your hair in the braids. Take the braids out and use gel, mousse, or hairspray to keep the wave in place.
If you want it to be gently wavy, do less braids. If you want it to look crimped, put more braids.