To help you categorize and organize your emails, in Horde you can create different folders for your email messages.  To create a new folder:

1. Select Mail on the left menu
2. Click on the Folders icon in the top menu bar
3. In the drop down menu under Folder Navigator, select Create
4. In the new box that opens, put in the name of the folder and click OK

For a demonstration, please see the video provided.