Here is the basic person to person defense set up in a standard (right handed) forehand force.
The Defensive player on the disc stands sufficiently to the side of the thrower and puts 100% of their effort in to not letting the thrower throw to this side of the of the field. I can not stress enough how important this role is. The rest of the team are essentially relying on this one player to make sure nothing gets thrown in that direction.
The downfield defenders then only have to stop their mark from attacking the open side of the field. Because they know the disc won't be thrown on the break side, it allows them to position themselves on the open side of their mark and make sure that they are ALWAYS in the way of their mark cutting and catching the disc on this side.
All of the downfield defenders except the last one mark underneath their mark as well, making sure that their mark cannot beat them when they cut towards the disc.
The last back defender sets up deep of their mark so they can make sure they cannot be beaten to the deep space.
If the last back defender's mark does go under, usually after a fake like this one.
The deep defender follows their mark under, keeping as close to them as possible while watching for other players going deep and CALLING an EARLY switch, OR watching for their mark to change direction and go deep again. Once the deep defender reaches the level of the stack again, the roles switch and the deep defender has to work to put themselves in front of their mark, while the new last back defender adjusts their position to now protect the deep space.
Reset.
The dump defender has the toughest task of all because he has to protect the entire back field. Realistically this is not possible and so a choice must be made. They can protect the open side space and make sure their mark does not get the disc up line or anyway on the open side.
BUT if their mark catches a dump pass on the break side they still have to work really hard to get the correct side force on before their mark can get a look on the break side of the field.
Or they can protect the breakside of the field and make sure their mark does not get the disc anywhere on the break side.
BUT they leave the upfield space open for the dump. they then have to work really hard to get a mark on before their defender can get a huck or break throw out.