Hi @Jennifer521,
No need to apologize - that is what this forum is for!
The guest pays the whole fee up front (well, on some areas, they are rolling out 50% at booking, 50% just before the trip, but a lot of people don't have that option yet). At that point, the company holds the money until the trip. They send you the payout 24 hours after check in, and then it arrives in your account 2-3 business days later. It has worked well for me so far (since March, 17 completed trips).
You have the strict cancellation, so if they cancel, they will get 50% back for the days that are more than a week away, and 0 back for dates less than a week away. Does that make sense?
Security deposit is a murky system here. They do not pay it up front. They just agree to pay if they need to, so Airbnb is not actually holding anything. If you need to claim it, put in the claim within 24 hours of checkout (so take a good look at your property when people check out). In my opinion, this is the flaw in the system. I have seen lots of complaints about headaches regarding security deposits.