On the rear of the swing arm on your Polaris will be 2 pinch bolts. Loosen them. This will then allow you to rotate the cam to allow for proper chain tension. When you get to where you want it, tighten the bolts back down.
My recommendation; Do it with a friend. Since it's your bike and your body weight, sit on the bike. You want about 1" up and down play WHEN YOU ARE SITTING ON IT.