Once the event has been created, you can view the event in the "Virtual Event" page.
Go to "Virtual Event" page and browse for the event you want to start. You will see the event will have "Start event" option listed on the right. You can click the option and start the event.
Alternatively, click on the event and then "More" dropdown option. In the bottom, you will see options like: Copy join link, Copy start link, Start meeting and Resend email Notifications. To start the event, click on "Start meeting" option.
Once you click the "Start meeting" button, the browser will prompt you to open the Zoom app. Click on the option "Open Zoom.us" and the meeting will be started.