Yes this is the way to do it. I've been shipping everything this way and haven't waited in a post office line in 15+ years. I just drop off all my packages in the drop boxes in the post office lobby or the outgoing mail at my office (I personally don't trust leaving high dollar items sitting in my mailbox out by the street, plus it's not large enough for boxes anyway).
A quick way to get to it is the URL which I keep saved in my favorites:
https://www.paypal.com/shiplabel/create/