What settings are needed to connect ethernet to iMac?

System Preferences

If you don't have an Ethernet option, then click on the + to add it. Use "Set Service Order..." to put the Ethernet connection at the top of the list.

Hi,

You don't need to settings, it's automatically connect to the Internet.

Just want to know how to connect Ethernet cable, I mean using Ethernet Hub or directly connect to your router port.

In order to be recognized by your router or modem, you need to make sure you have a plan/contract with your internet service provider who, in turn, will make sure that you have a connection.