At a first glance creating and developing a database profile in XML may seem difficult. However, all definitions forming the functionality for a specific database are expressed in a single file and the XML elements are well formed. The general recommendation is to use one of the existing database profiles as base (copy/paste) and then step-by-step modify it for the actual database. You may use an external text editor (preferably with XML support) or the SQL editor in DbVisualizer to edit the file. Once new changes has been made, save the file, reconnect the database connection in DbVisualizer to test the layout and functionality changes.
Creating a new database profile should only be made for databases with no database profile available. If you are looking into changing one of the existing database profiles by adding or modifying existing functionality, it should be extended.
For information where custom database profiles should be saved check the How a Database Profile is loaded is section.
For more information how to create a new database profile or extending an existing database profile check the Extending a Database Profile section.