I was wondering what the DC number is and where you get it from, etc?
DC# is the delivery confirmation number. When you go to the post office just tell them you want a dc#. The have alittle paper thats white, black an neon green that they tear in half. One pice goes on your package and one piece goes to you. The piece that goes on the package has a barcode on it with numbers that is scanned periodically during its delivery. You can go to the usps website and type in the number under the 'track a package' section and it tells you where the package is at, and where its been. (sometimes they dont scan it like they are suppose to though) But its basically proof that you did send a package and shows when the package was delivered to its destination.
Edit: on the piece of paper that you keep, it has the same number as the other 1/2 of paper that was put on the package. So just keep it, and use that number to track its status.