Hello,
We are Glad that you resolved the issue by yourself. You are great!!.
I saw the screenshot you attached. To Populate the promo popup area you need to create an HTML Block from Dashboard >> HTML Blocks.
Screenshot for Clarification: https://www.screencast.com/t/dZ7d7PWyw
Then you need to add the ShortCode of the HTML Block to the Promo Pop up from Theme Settings >> Shop >> Promo Pop up.
Screenshot for Clarification: https://www.screencast.com/t/86C9qwTXVs4
If you want to use image or color as the Promo Pop up Background. Then you need to scroll down and set Pop Up Background as well.
Screenshot for Clarification: https://www.screencast.com/t/fylfuqrM
You can also use our ready to use Promo Pop ups HTML Blocks that come with demo import.
Screenshot for Clarification: https://www.screencast.com/t/IMEsA8X2k8o
Best Regards.