If you're account is setup to allow for will call labels at shipping, you will receive a modal when you scan a barcode to ship as shown below:
If you select Print Label, you will get a zpl label to print to go along with the order until the customer picks the order up:
Once the customer picks up the order, scan the barcode into Turbine either in the Production > Ship screen or the manage screen to access and order and mark it as shipped.