I installed correctly but, every time i click the icon it gives me an error : ''Please insert the correct cd - rom, click ok and restart the application ''... i need a crack or something?? please help !

Did you ever play this game from the cd version on the same computer before trying to run the gog version on it? If so it could be a problem with registry settings.

You didn't patch the game first, did you? Because patches would be for the CD version of the game and will often replace the main executable - bringing with it the disc checking DRM. If so, just uninstall the game and reinstall it without the patch.