For the printers that are directly on the Ethernet network:
Open the Printer Setup Utility on your Mac
The printer may appear automatically. If not, click "add", select "IP Printing" and enter the printer's IP manually.
Once the Mac sees the printer, it will ask you to select the right driver and give you a long scrolling list of the installed drivers. If your printer isn't on this list, you'll have to download the Mac driver software from the manufactirer's website, install it on the Mac, and then repeat. However, drivers for most common printers are pre-installed on the Mac from the factory.