In this case, we will be forcing flick (in general, most players are right handed). In this scenario, Red is on offence and is attacking the endzone at the bottom
On our force flick, our mark (player 1) is on lined up with the opponents left shoulder, with the middle of their body square to opponents shoulder. The goal of player 1 is to prevent any throws through them (in this case, to the right side of the field). The other defenders (Players 2, 3 and 4) are marking the "open" side of the field (which in this case is everything to the left of the red player). The goal of these players is to not allow their mark to get the disc on the left hand side of the field. Player 2 can leave a little bit of extra seperation between their person and themselves, as the mark is responsible for making sure no throws come across the field.
As red makes their cuts, defenders stay on the open side of their person.
Another rotation of cuts. It is very important for player 3 to stay in front of their person, as the in cut on the open side is the easiest pass to make!