dillydally wrote: ... I cannot see it in the Configuration?
It's not in the Configuration, but as Nicolas said, it's the "Product type" option of your products. So, you got to go and edit your products and set that option to "Shippable goods", then the weight and dimension fields will become visible and accessible.
(With many users here being irritated or even unable to find the weight/dimension fields, maybe HikaShop wants to consider making "shippable" the default choice instead of "virtual". It's been asked for before, but without success so far...)