This simple tutorial assumes you already have a working PHP installation. There's plenty of guides on how to set up PHP, here I'm only showing how to make it interact with Firebird.
Requirements
* PHP
* Firebird SQL
Install Firebird SQL
* Download the zip archive: Firebird SQL 2.0.0
* Extract the archive to C:\firebird (for instance)
* Open a command prompt window (START, Run, "cmd")
* Run these commands, one by one:
C:\firebird\bin\instreg i
C:\firebird\bin\instsvc i -s -a
C:\firebird\bin\instsvc start
Configure PHP
* Copy C:\firebird\bin\fbclient.dll to your C:\windows\system32 directory and rename the file to gds32.dll
* Copy php_interbase.dll from your php\ext directory to the C:\windows\system32 directory.
* Copy libeay32.dll and ssleay32.dll from your php directory to the C:\windows\system32 directory.
* Edit your php.ini, un-comment the line
extension=php_interbase.dll
(you have to remove the semicolon from that line).
* Restart your webserver (Apache).