Task: I had to travel to Japan for some official purposes. Search for a flight from Denver Airport to Japan Airport on October 28 for 1 adult in the Economy class in the Booking.com app.
Steps:
Open the booking.com app
Click on the flights tab
Click on the one-way option.
Click on the starting point
Click on the cross icon of the DEL section
Type Denver in the search bar
Click on the check box 
Click on the done button.
Click on the where to in the search bar
Type Japan in the search bar
Click on the check box of the first result
Click on the done button.
Click on the calendar section
Swipe done for the October calendar 
Click on the 28th date of October 
click on the done button.
Click on the search button.
Click on the search button.