When you log in to your paypal click on Merchant Services.
There will be a menu and under shipping and tax there is a link for "Multi-Order Shipping"
Click on that and you can input addresses and labels, then check out all at once. It automatically adds delivery confirmation for the 18 cents.
Then you print out the label and tape it on the package.
You can input the weight/dimensions, but since we are using a flat rate just check off flat rate.
After you use it once it will be in the upper left hand corner on your account overview page.