If you have installed/enabled the built-in warehouse management system (WMS), you can create the Item masters manually or import their details i.e. Item code, Barcode, Description, Sales unit price, Purchasing unit cost, etc.
To set the stock levels, at this stage, and to simulate the real world the most practical step is to create a Purchase Order on the Supplier you created in a previous step. You can then receive the stock via the Goods In tab on the Warehouse management console.
Note in this example, the stock value is not adjusted. See this next video to understand two different methods for recording the value of the incoming stock in the Stock Asset account in your balance sheet on your general ledger.