Do you have a scale so you can be accurate on the weight?
I just log in to PayPal and then click on "multi-order shipping". (If you don't see it, click on "Merchant Tools" across the top to get to it.) Entering the info is pretty self-explanatory. When you get to the next page, click on "print and pay" to get a drop-down window and click on "print and pay" again. Basically it pays for the postage from your PayPal account, and then you get a window to print out the label. I tape all across the label and along the sides except for the bar code; it's best to leave the bar code untaped so the machine has no trouble reading it. I usually wait until I have the label taped on before getting out of the program, just in case I need to reprint. You can reprint even if you get out, but it's a little more complicated to get back to it.