> How to connect to the Fireberd from android application ?

Class.forName(FBDriver.class.getName());
Connection connection = DriverManager.getConnection("jdbc:firebirdsql:192.168.3.22:employee", "SYSDBA", "masterkey");

> Where does Firebird run?

Firebird run Linux server
Plan to use connects via Wifi networks connection (Android 2.2)