To set inventory levels on a product, click the products icon in the Left Navigation Menu on your store's Dashboard page.
Click the product you wish to work with and on the product Detail page and scroll down to the Inventory section. Click the Start Tracking Inventory button.
Using the Up/Down arrows to the right of Quantity set your current stock for the product. Click the Set button once you have entered your stock.
Click the Save button at the top left of the Product Detail page to finalize your changes.
Your product's inventory should now show the stock quantity you entered as well as a new section that allows you to update quantity as needed.
When viewing the product on your storefront, the stock quantity you entered will be visible above the Add to Cart button.
When an order is placed for the product, you will need to fulfill the order to change stock status. From your site's Dashboard, click the Orders icon from the Left
Locate the new order and click to open its Order Detail page. Click the Accept Payment button to start the fulfillment process.
Scroll down to the Unfulfilled Items section of the Order Detail and click the Fulfill button.
Depending on how you get your products into the hands of your customers, your process may vary at this point, but for Curbside Pickup or Local Delivery, click the Mark as Fulfilled section. You may also want to uncheck the "Send shipping notification to customer" box if the item is being picked up or delivered locally. Click the Fulfill button to complete the order. You should see an Order Fulfilled pop-up on your screen.
Depending on the number purchased, the product's stock quantity will change accordingly.
The In-Stock amount shown on the storefront will also change.
Once all your stock quantity has been sold, the item will show Out Of Stock on the storefront and the Add to Cart button will no longer be available.
Each day as you replenish your stock, just go to your product and add the new stock in the Inventory section. Your store will keep track of it and make sure when you sell out no one else can order it. You can also add stock during the day if more becomes available.