.  Go there and then click on "Manage" for the layout you are using. Layout 1 is the default which is shown here. 
Property Description - Booking Page 1This module can be shown at the top or the bottom of the booking page. 
It will only show if it is activated in 
SETTINGS -> BOOKING ENGINE -> PROPERTY BOOKING PAGE -> LAYOUT.  Go there and then click on "Manage" for the layout you are using. Layout 1 is the default which is shown here. 
The content can be entered in 
SETTINGS -> BOOKING ENGINE -> PROPERTY BOOKING PAGE -> CONTENT