If you want to add an attribute at a time of item creation then,
1.goto Master > Item > click on the New button, and fill the item details in which you can see two fields related to attribute
a. Stock Attribute group: to maintain stock you can use Stock attribute Group
b.Item attribute Group
2. There are some predefined attributes you can select any of them or you can create a new attribute for that type new and then select ‘New Attribute group’ and fill the details of attribute press on ok.
3.Press on the OK button of Item Frame.