Form using Database insert: instructions needed

I’ve rummaged through the Wappler docs (older versions of Wappler) and youtube tutes (out of date) and can find nothing on how to send data from a Wappler form to a SQL Server database. I’m using v5.1.4 and the docs do not address this version.

This should be easy if I can learn how a Wappler form connects to an insert query I’ve created under “api”. My attempts at this have failed with the error shown below.
Thank you for any help with Wappler forms.