If your website is configured correctly, you can add your product into more than one category.   This is done via the Multi Cats tab when you are editing a product.

Categories listed in the box to the left are all of your categories, and the list to the right are categories that your product will appear in.  When you have finished click on Save or Cancel.

The buttons are labelled as follows:

• >  - Move selected item to the right
• >> - Move all items to the right
• <  - Move selected item to the left
• << - Move all items to the left
• Save - Save changes
• Cancel - Reset to the positions they were last saved as