The most powerful feature in the Tree Schema API is it’s ability to programatically create and manage data lineage. Most of the other features: managing data stores, schemas and fields are much more efficient to do through the Tree Schema GUI because you can point Tree Schema to your database and Tree Schema will collect the metadata on your behalf and populate your data catalog for you. You can learn about the automated connections in the first two sections of the Tree Schema 101 tutorial.
However, in order to build data lineage programatically you must first have an understanding of the data stores, schemas and fields that are linked together. These examples provide a comprehensive overview of all of the API features.