Not every shipping method has a tracking number. (see shipping methods)
If your shipping method has tracking, you can find the number in the shipment notification email that is sent when you order is shipped.
You can also login to your account at www.pumpunderwear.com/store > My Account > My Orders. After you select your order from the list choose > Shipments > Track to open a window showing the status and whereabouts of the shipment.