First of all how do you distinguish between a male and a female shark?
Unlike men, male sharks have two penises (alright not exactly penises but a pair of claspers -see figure 1) you can see them as flaps lying flat their bellies nearby their pelvic fins. As for the females, they have an opening instead of these flaps to its cloaca.
|Figure 1 - External features of a male shark, bottom right photo shows the Claspers|
As seen on the video, the male bites the pectoral fin of the female, arching its body in a manner that his claspers come in contact with the females’ genital opening. I will let the video do the talking for me :P (video by youtuber )