End to end create model using MDS API

Please can someone supply an end to end example of using the MDS API to create a model, entity and attributes on the entity?  I'd like particularly to also see how to create relationships between entities (Person to OrgUnit for example) using the API.

I have written code to create a model, entities and attributes, however, I can't see attributes of my new entities in the MDS website model explorer. If I manage Entities, then I can see that the attributes exist.

Apologies for number of edits on this post, but I'm learning and up against a deadline. Nothing new hey!