New to Map Enterprise / Schema questions

Old Microstation 95 developer here . Our office is in the midst of upgrading from 95 to Map Enterprise/ Descartes. We're still very confused about Geospatial Admin / Schema. I'm less concerned with creating a schema and more concerned with how to use it. If were going to be attaching shapefiles as reference files when exactly does the schema work it's magic? When we attach the reference shapefiles there's nothing that says "Apply schema".