How to get a Mac to recognize Windows PC on network?

After you have the workgroup’s name, go to the Mac, open the system preferences and click on “Network.”  Next, click the connection (either Wifi or Ethernet), then Advanced, then WINS. There should be a control panel that has an entry for “workgroup.” Check to see if the name of the PC’s workgroup is in the drop-down list. Select it if it is, type it in if it is not. Click on OK and Apply, and the PC should now be in the Sidebar.