How to add a stock item and its opening quantity
A tracked item keeps its quantity on hand and posts its cost when it is sold. Add it, then bring in the stock you already have.
Steps
Add the item
Under Inventory → Items choose Add item; give it a name, code, unit and selling and purchase prices, and keep it tracked.
Choose its warehouse
Stock lives in a warehouse: add one under Inventory → Warehouses if you have none.
Enter the opening stock
Under Inventory → Inventory adjustments choose New adjustment, add the item with + quantity and its value.
Post
Choose Post: the stock moves and is booked against the account you chose, such as opening balances.