This article details how to connect a USB printer to your Mac. For most USB printers, all you have to do is update your software and then connect the printer to your Mac. The MacOS software will automatically detect the printer and download any necessary software.
1) Update your Mac software by navigating to the Apple Menu and going to System Preferences
2) Choose Software Update and install any software updates listed
3) Connect your printer to your Mac via USB
4) If prompted to install software, make sure to install the printer software. That's it!