Its is very simple.
1. Connect an ethernet cable to both computers
2. Go to system prefrences and click on the Sharing Pane and make sure Personal File sharing is checked off.
3. In finder on the top menu bar choose Go > Network and the other computer should come up there. Double click it and login to it.
If your Ethernet port is being used for your internet connection we will need more info about your home network to get them sharing files.
hope that helps! 🙂