To do this, open the Network and Sharing Center and click on Change adapter settings in the left pane. you should see a list of network adapters. Press the Alt button (if the menu bar is not already visible) and click on the Advanced menu, and then choose Advanced settings.
A new control panel will pop up, and you should see it open to the Adapters and Bindings tab. In the top list should be a list of your network adapters, with an up and down arrow button to the right. This is the priority order of what adapter it will use when connecting to the Internet. Choose your Ethernet adapter and click the up arrow button until it shows at the top. Then click OK.