You access the Jamf Pro API by the following URL format: https://yourinstancename.jamfcloud.com/api (assuming you're on Jamf Cloud. If not, it's your regular instance with the /api suffix all the same).
I'd recommend checking out the possibilities there, as you can interact with the various endpoints (things you can do in the API) using the UI of that webpage. There's also documentation, and you can do some quite powerful things with even just a little knowledge. The boards here will also have a lot of information you can search for.
The Jamf 400 course focuses on the API a lot, and it is an advanced subject but take baby-steps and work out the solution to your current problem and then you'll be well on your way 😊 In fact, it's good general knowledge for RESTful APIs as a whole, as that's what they are.
