I would like to create/update events in CiviEvent by using Eventbrite webhooks. One of the requirements is having an endpoint page that will receive data sent by Eventbrite API.
How can I create that endpoint page within CiviCRM?
You will need to create extension to have Eventbrite sync with CiviEvents. Here is some guideline on how to approach this
Mandrill extension uses same approach i.e to create entries in various civicrm table upon webhook call. This might find you helpful to develop your extension https://github.com/JMAConsulting/biz.jmaconsulting.mte/blob/master/CRM/Mte/Page/callback.php
There is now an extension for EventBrite integration.