As of a few years ago, it went something like this:
The first afternoon you arrive is mainly getting acquainted with other folks in your element, your element leader (who will be a cadet) and getting your 'uniform', getting to your room, etc. If I recall there is a briefing as well.
The first full day was a taste of basic cadet training/fourth class year. Memorable and a great experience to have while assessing if USAFA is the place for you.
The other days include morning PT, briefings, teambuilding activities, attending mock-classes, going on hikes/seeing base, etc. I realize that isn't very descriptive and I'm sure someone who went more recently can give you a better idea.
Long story short, it is a great week which answered lots of questions about cadet life. Enjoy!!