Databases are usually stored in a data center like MySQL, PostgreSQL, Oracle and so on.
When you say that you created a database in Dreamweaver and want to move it to FBPHP - what exactly do you mean?
Yes the database is Mysql? Is there a way to convert it, or do I have to start over from scratch?
MySQL has nothing to do with Dreamweaver or any other development software. It's a DBMS (which stands for DataBase Management System). More simply, it's a way to store data. Other DBMS are PostgreSQL, Oracle, and so on..., as mentionned above.
To use your existing MySQL database with FlashBuilder for PHP, simply specify where you store your PHP services on your computer when you create your project. Then FB will attempt to connect to MySQL with the help of your PHP code.
And you'll be able to retrieve your data in the brand new Spark Datagrids !
Hope it'll help.