Using with OnCanvas theme and blocks

I am having real trouble figuring out how to do this with a backend that is set up in blocks and not like the screenshots showed. I can’t find a way to do custom fields nor do I have meta boxes. I literally just want to be able to embed a link from my society6 sales page with all of my art prints and things that are available. I thought that this would be an easy fix and clearly I am missing something somewhere.

The page I need help with: [log in to see the link]