Once you have some exhibitors invited, they can start making booths. However as the event admin you can also do that yourself.
Click on the BOOTHS tab in the side menu.
Click NEW BOOTH in the top right corner. A pop-up will show up prompting you to fill in the details and assign a host. The host can be anyone in the organization that you selected. Admins, Exhibitors, Speakers and Participants can all be booth hosts.
When you are done with the details click SAVE. Your new booth will show up in the booth list.
Booths are organization specific. Before choosing a host, please select the organization they belong to. As part of your booth you can upload an image or video that will be displayed to people when they visit your booth.