Let’s say you want to create a new event, but you are not yet ready for it to go live. You can ‘Save Draft’.
On the right of your ‘Add Event’ page is a ‘Publish’ box. Within it are several buttons.
Save Draft
Preview
Publish
… see below…

Save Draft – this allows you to save the Event, and leave it. You can come back to it when you are ready to finish it off.
Preview – once you have entered all your details into the Event, you might want to see how it looks – click Preview and it will open in a NEW TAB, and you can see how it looks. Return to the *other tab* to make final changes.
You can also use this button if you are Editing a live event, just to see how your changes might look – to preview how your Event appears to readers.
Publish – you are ready for your Event to go live on the website. Click Publish and it’s done!