Hi Michael,
Thanks so much for reaching out!
Just to let you know, we are limited by our Support Policy in how much we can help with customizations, but I will try to point you in the right direction.
You can start off by taking a look at our Themer’s Guide, which can walk you through how to copy and edit our templates to suit your needs. You’ll want to look at the /wp-content/plugins/the-events-calendar/single-event.php template.
Once you’ve got the template set up, you can create a custom sidebar by following these instructions, and then add it to the template by using get_sidebar. Once this has been done, you should see your custom sidebar appear in the widget area, where you can drag and drop widgets into it like any other sidebar.
Let me know how that goes!
Thanks,
Jaime