Hi @Debra72
I am not quite sure if I understand your question, but here goes.
As you'll know from being a host, the guest normally pays in full upon booking. But in some cases there will be an option for split payments, when bookings are quite a long way in advance. (see Airbnb Help Centre).
Again this is something you will probably know from being a host. Hosts set whatever deposit they like, and this is something Airbnb doesn't charge on booking, but is an amount that can be charged if there is damage etc and Airbnb finds that the guest is at fault (see Airbnb Help Centre).
Does that answer your questions?