The receipt printer plugs into the USB port of your  computer.

Install the software that came with the printer. Setup varies  by printer type, typically from Start, Control Panel, Printers and Faxes you can right  click on the installed printer and go to Properties. Here you should find  settings to activate the Cash Drawer.

Please contact the manufacture of your receipt printer for  help on how to install the software.

Once the receipt printer is setup, whenever you select to  print a receipt you will be asked to choose which printer you want to print  to.