Attributes

I'm trying to create a attribute product  with a different SKU (for the purpose of controlling my inventory in colors and shapes) but I have difficulties to do so. I would like for some help in that matter and if there isn't have such an option/function I would like to create one.even if I need to pay for that service
Thanks.

You can change the inventory tracking method for a product in Product Info > Inventory > Inventory Method

here is the documentation: http://docs.nopcommerce.com/display/en/Inventory+management