Here's how it works:
1. You tell your friend to apply to hih_animagus, and tell them to put "Referred by: [your username]" at the end of their application.
2. Your friend applies.
3. You get a credit worth five bonus points for the following month's activities at hih_wilderness. This means if you do both activities, you will get 10 extra points for that one referral! Easy, no?
Some questions I know you are itching to have answered:
You may only get credits for one referral at a time. You may refer someone new every month. It doesn't matter which batch your friend's app is posted in. Whenever their app goes up, you get bonus points for the next two activities in Wilderness. It also doesn't matter if your friend doesn't like their choices or turn in their essay. They apply, you win. However, a person may only be referred once. So if they reapply later, no one gets points.
Your referral credit expires after two activities have taken place. You don't participate, you lose the bonus points. You want new bonus points, you refer someone else.
Referral credits will be noted on the (newly spruced up!) animagus list on the profile page of hih_animagus. A pawprint next to your listing indicates that you have bonus points. You can mouseover the pawprint to see if you have credits for one or two activities remaining (it will say which activities you have left, like "Month 1 and 2").
Questions? Ask them here! :)