How do I print on both sides of the paper (duplex) manually on the HP LaserJet P1102?

Load paper face-up in the input tray, then open the printer driver and click the Properties or Preferences button, and click the Finishing tab to select manual duplex printing. For Mac users, after printing the first side, take the printed stack from the output bin and insert it printed side down into the tray with the top edge feeding into the product first, then click Continue at the computer. (Page 55)