You can categorize your artwork by using the Album feature.
To create an album, navigate to your Portfolio Manager.
On the left side of the Portfolio Manager, you have the option to create and manage albums. Click on "Create new album" and name it. If you have the Pro Account, you will have the option to select its visibility. Click save once you are done.
When you have created your Album, you can just click and drag the Project into the Album folder.