Where to find and use the newly improved data model editor from Business Central application in BRMS 6.1 ?

Issue

• New users of the improved Business Central UI in BRMS 6.1.0 can't find how to view the data model for creating/editing it. How to create or modify data model in the new Business Central UI in BRMS 6.1.0?
• In Business Central application after creating a data model it create a java class for it's objects . For some users their data model objects will be created from a database by hibernate plug-in in Eclipse , because they might not want to create them manually. How should these users import them later to the Business Central UI ? Will such users be able to create them in the UI in the same way like they create a data model from the UI ?
• Can users mix data model with objects imported (as mentioned above) and object created from the UI?