API Create Report of Learners Enrolled in Course but not Session

I was told by Docebo help the following is possible with the API but I lack the knowledge.

We have an ILT course that employees have been enrolled in. They have gotten an email asking them to enroll in a session. I’ve been tasked with creating a report of those learners (along with their manager’s names) who have not enrolled in the sessions.

Where do I start? Is there a Docebo API 101? What is in the knowledge base is more confusion than what I read in the Docebo API Explorer.

Do I write JavaScript to GET the information via the API? Does anyone have sample scripts they would be willing to share?

Thanks