Hi,
after you've installed FireBug and FirePHP move the Foleder "FirePHPCore" to your PEAR Folder.
Inside your script you have to incldude the FirePHP Library
require('FirePHPCore/fb.php');
Now you can your FirePHP in your script:
fb('Log message', FirePHP::LOG);
fb('Info message', FirePHP::INFO);
fb('Warn message', FirePHP::WARN);
fb('Error message', FirePHP::ERROR);
There are altough other ways, many Frameworks are supporing FirePHP out of the box, like the Zend Framework.
$fb = new Zend_Log_Writer_Firebug();
$logger = new Zend_Log($fb);
$logger->log('Log with Zend and FirePHP', Zend_Log::INFO);
Cheers,
Arne