Click the 
Stock icon on the top toolbar. (Or you may have followed a shortcut from the Catalogues screen > Stock mini tab)
Follow the steps below when in the Stock screen to create a new stock record. You must do this to an an item into stock for the first time.
1.Click 
Add and answer "yes" to show the product selector.
2.Use product search to locate an item
(If the product you require is not in the list you need to add it to My Catalogue first).
3.Click Select Product to bring the New Stock Item window
4.The code, desciption, colour and manufacturer will be completed but can be edited if needed. Dimensions are optional.
5.Select a Location. To edit location click 
Edit Popup Contents to add new locations.
6.Select a Category. To edit location click Edit Popup Contents to add new locations.
7.Enter an opening stock quantity.
8.The cost price will already be completed and this can be left or amended.