Refer to the below attached video for the same,
If you need to update any data for a particular day, you can use Rates & Inventory and update data for particular days.
We can see 15 days here, so you can update a calendar and click on next to update the next 15 date data.
Select a particular date and update your value, after that click on save to save data.
Source: Select your source, OTA Common pool to update data for OTA, Web source to update data for the booking engine.
Rate/Extra Adult Rates/Min Night etc: Select you operation from dropdown and update.
Copy: If you need to copy the same value for the other 14 days, enter a value for one day and click on copy the same value on other dates.
Multiply/Addition factor: If you need to add or multiply your rates direct, you can add value here and it will update rates as per multiply/addition factor.