Schema objects are maintained from the System Setup tab. Examples of such objects are Attributes, Action Sets, Contexts, LOVs, Object Types, Tags, Units, Users & Groups, Workspaces, Reference Types, and many more. Most actions performed require Super User access. This is where the core components like integration endpoint, STEP Workflow, Web UI, business rules, etc. are created and configured.
Additional information on the System Setup objects and functions can be found throughout the online help. For example, information on workflows is available in the Workflows guide (here), while information on integration endpoints is available within the Data Exchange guide (here). Information for general functions that are not covered in independent guides (e.g., attributes, references, users and groups) can be found in the System Setup documentation here.