The repository database can be an existing MySQL, MariaDB, PostgreSQL, SQL Server, or Amazon RDS instance. If it scares you, it might be a good thing to try. It is used while your ISPs do not allow direct connections, but allows establishing HTTP connections. The Main Window consists of several toolbars and panes for you to work on connections, database objects and advanced tools. Actually it is just in an idea when feel oneself can achieve and cannot achieve. In the Objects tab, you can use the List List, Detail Detail and ER Diagram ER Diagram buttons to change the object view.