You don't need to concern yourself with the file names. MySQL server takes care of all those details for you.
Each database is given it's own folder, and each table in the database has files in that folder.
There can be files with table structure, table data, table indexes if you use MyISAM engine.
If you use InnoDB, then you'll have structure file, but data and indexes are contained in a file managed by InnoDB, usually ibdata, along with 2 ibdata logfiles.
But yu don't need to worry about any of those details, just enjoy using MySQL
There should be a mysql folder, which contains the database mysql uses to keep track of itself, and users access and privileges on the system.
There should also be a test database, with no tables in it. That's for you play around in and work stuff out before adding it to your "live" database.
To find out more, start with MySQL reference manual in general, and the tutorial chapter in particular.
http://dev.mysql.com/doc/refman/5.1/en/tutorial.html
Good luck,
Barry.