If you find a date available that will work for your group simply call Mike directly toll free: 1-866-724-2356 x 106 or locally 920-684-0218 x 106. (note: if you leave a message, and I get someone before you, I have to take reservations in order) Unless stated otherwise, an open night has 65 spots total. Nights with no description (typically weeknights) are open for bookings as well.
You can also email Mike with your date choice and estimated number of participants at email@example.com. If you are doing a Group Overnight, please make sure that you have also read over the Group Leader's Page so that you understand pertinent deadlines and to print out the necessary paperwork.
Please note: Unless the date specifies that it is a Family Overnight (marked as "FON-# spots open"), it is meant for large groups such as Boy Scouts, Girl Scouts, Church groups, History Clubs, Family Reunions, or other large groups. Family Overnights are usually late July to early August, and meant for individuals and small non-organization groups.