Follow below mention steps to get your Eventbrite Organiser ID:
Step 1: Go to Eventbrite Portal https://www.eventbrite.com/
Step 2: Enter your Eventbrite Portal Account details and log in. If you are not registered, create a new account by clicking on Sign Up button
Step 3: Once you have logged-in into Eventbrite Portal, click on Organizer Profile link
( Note: If you are not able to see Organizer Profile, then you have to create an event in your Eventbrite page . For creating an Organizer go to Manage Events>>Create Event section. )
Step 4: At the bottom of the page you will find your Organizer ID