When someone purchases your product you will be able to generate and download the shipping label directly from your dashboard based on the buyer's address and the shipping information you put in when creating the product.
As you can see in this example, the buyer will be presented with shipping options based on the data provided when purchasing from you
Once someone purchases a product you will be able to go to the shipping tab to see and print the label
You can see here the shipping tab will have all the information on the order, date, customer, ship to, which carrier they selected, shipping status, and shipping cost.
Simply click more actions to activate the drop down menu
From here first select Create Label, which will generate a shipping label
Once the label is generated the status will change to Label Generated which you can then download
Sample Shipping Label
Once you actually ship the product go back to your dashboard and mark the order as "complete". Once the order is marked as complete meaning you have shipped the product the buyer will receive an email with the tracking information