Click on “Products” and go to “Product”.
Double click the item that you want to modify.
Or click “Add” to add a new item.
Then when you on the item modification page, click “Product Price”.
Select the attribute and click “Add”.
Then you can select attributes from this category by ticking those you need.
Then attributes are assigned to this item.
If you want some extra charges for a certain attribute, you can click “Edit”.
Put a price here and save.
Click “Save” to save your changes.