Each time you start working on a new production, you create a new project that is saved as a PDS file and is used exclusively by CyberLink PowerDirector. Use the buttons to save, create new or open existing projects within CyberLink PowerDirector.
The changes you make to your media in CyberLink PowerDirector do not affect the original media you imported into the program. Since your settings are all saved in the project file, you can trim, edit or delete clips, but still keep your original files on your hard drive, untouched. So let yourself get creative. If you end up changing things too drastically, you can always start over.