1. Visit the United Airlines Website:
Start by visiting the official United Airlines website at www.united.com.

2. Begin Your Flight Search:
Enter your departure city or airport in the "From" field and your final destination in the "To" field. This will be the last city you plan to visit.

3. Select "Multi-City" Option:
Click on the "Advanced Search" or "Multi-City" option, usually located below the standard one-way and round-trip search boxes.

4. Add Your Destinations:
You'll now have the option to add multiple destinations and stopovers. Enter the cities you wish to visit, along with your preferred travel dates for each leg of the journey.

5. Customize Your Itinerary:
Once you've added all your destinations and dates, you can customize your itinerary further by choosing flight times, cabin class, and any other preferences.

6. Review and Book:
After inputting all your travel details, review your itinerary to ensure accuracy. Then proceed to book your multi-city flights.