You can toggle between having a private or a public event by setting or removing the tick in the tick box 'Public' at the top of the Create/Edit event screen.
If your event is already up and running or saved as a draft you can get back to the Create/Edit event page by:
- Clicking on Calendar in the top left corner of the screen
- Clicking on Edit next to your event (if your event is not immediately visible, try clicking on Draft from the options along the top of the screen)
- Hit Publish to update your changes