The first step will be to update the Booking Date to the new arrival & departure date.
You can change a Booking date from the Booking Summary page:
Click on the Booking Date
Make the required change
Click Save
Then you should Add a Group to the Booking
From the Booking Summary Page:
Go to the Groups section
Click +Add Group
Fill out the respective fields for the group
Select Add/Edit Room Rates
Select +Add Room Type
Select the Room Type
Enter the Room Rate
Repeat steps 2-4 for any other Room Types
Click Okay
Enter the number of Blocked rooms for each Room type, on each day
Save the Group