For bookings made via API or shopping cart plugin, head over to the New Orders tab. Here you will see all of the orders that have been sent into Shippit for processing. Beside each order is a green Label button under the Controls column. Clicking this button generate a PDF Label that you can print out and placed onto your parcel.
For bookings made using the Send process, once you have booked an order, you will find the "Print Shipping Label" to the bottom left of the confirmation screen. When clicked, this button downloads a PDF label for the order that was just created.
Once in "Ready for Pickup" state, you can download a labels from the Track & Manage page. Clicking on the blue drop down button to the right of the relevant order will give you an option to download the label for that booking.