What is the best way to add a new Entity to the model?

Hi everyone,

What is the best way to add a new Entity to the model and store it in the database? I would like to add a custom table with a column id that is autoincrement. Thanks in advance for your help.

I have found this: https://www.keycloak.org/docs/latest/server_development/index.html#_extensions_jpa I think is a good starting point.