To book a United multi city flights ticket on United Airlines, you can follow these steps:

1. Visit the United Airlines website and select the "Book" tab.
2. Choose the "Multi-city" option instead of the "Roundtrip" or "One-way" options.
3. Enter your departure and arrival cities, as well as your travel dates, for each leg of your trip. You can add up to six different cities and dates.
4. Select the number of passengers traveling with you and choose your preferred cabin class.
5. Click on the "Search" button to find available flights for your itinerary.
6. Review the flight options and select the ones that best fit your schedule and budget.
7. Enter your personal and payment details to complete your booking.

Alternatively, you can contact United Airlines customer service and speak with a representative to help you book a multi-city ticket. They can provide additional information, answer any questions you may have, and assist you with the booking process. To know complete information about it read the full Blog.