Create a new product class/category and assign to an item
Create a new product class by going to data maintenance, selecting product category from the drop down and then clicking add new. Once the product category is added, you can assign it to the item in item data maintenance.
If an item does not have a product class, you may use the steps above to assign an existing class. Please note that once the product class is applied to the item in your ERP, it will replace the assigned value with the next data refresh.