All documentation related to how the scheduling algorithm is designed can be found here.
On the Concepts page a description of all abstract concepts can be found.
On the Algorithm Overview page these concepts are used to describe step-by-step how the scheduling algorithm works.
The pdf ZinZen Algorithm Test Case Simple visually represents an algorithm test run scheduling 3 simple goals. The PDF contains a detailed description of each step and is a good place to start understanding (a simple case) of the algorithm. It does contain a small error - can you spot it?