Video tutorial:

1. Login to the events admin module
2. Go to "Manage events"
   
    
   
   
3. Search for your event by using the search criteria
4. Click on the name of the event to show the details (if they are not displayed yet)
5. Click on the "Edit" button on schedule level
6. Change the flyer by clicking on "Choose File"
7. Make sure you upload an image file that is not too big (around 300KB is recommended to load quickly on mobile devices)
8. Press "Save schedule"