If your existing categories do not yet include the category you wish to use, you can create new categories on product or material card.

1. Create a new product or material card or navigate to an existing card in the "Items" screen.

2. Type a new category name to the Category field.

3. Your category will be saved automatically.

Alternatively, you can create new categories in "Settings" -> "Categories". There you can also edit and delete your existing categories.