How to use Lazarus with Firebird?
Lazarus is a cross-platform clone of Delphi, so most of Delphi concepts and documentation should work. For example, you can use TIBConnection, TSQLQueery and TSQLTransaction components that are included with Lazarus for data connection and use TDBGrid, a TDBNavigator and TDBEdit as visual controls.
Some users reported success with recent versions of ZeosLib, so you might want to look into it:
Some of the component libraries listed in FAQ #7 can also be used, so make sure you check them out. Getting some book on Delphi is also a good idea.
Detailed guide explaining how to use Lazarus with Firebird Embedded is available on the following page: