Maintenanceman.nl has a number of tutorials published on it’s website.
To get up and running quickly, it’s recommended to read:

1. Getting started
2. Setting up your first API request
3. Understanding your first response

And if you want to dive deeper:

1. Deep dive one: consequential executions
2. Deep dive two: reset prevention and merging

Not a programmer, but still interested in using Maintenanceman.nl API?
read ‘Using the API from a spreadsheet’!