To add an overall ticket quantity to your event first navigate to your dashboard.
Click Ticketed Events in the menu on your left. Then, choose Manage on the event you would like to edit.
Now head to the Tickets tab of your event
Select the ticket whose quantity you would like to adjust by clicking the Edit icon at the top right of the ticket type, indicated by the pencil.
To add a ticket quantity, edit the number in the Quantity field. To adjust the number of tickets with each purchase, edit the Tickets Per Package field. To finalize, click the blue Save button at the bottom of the page, and you're done!