I'm assuming that your TV is too far from your router to easily run an Ethernet cable.
Open Control Panel> Network and Sharing Center and click Change adapter settings.
Shift-click to select both your WiFi and Ethernet adapters. Release Shift and right-click on either adapter and choose Bridge Connections. You should end up with a new icon labeled Network Bridge.
Connect your TV to the laptop using a Crossover Ethernet cable. A standard Ethernet cable will not work.
You could also use a WiFi adapter for the TV. Check with the manufacturer to see if they offer one for your model (it will usually be a USB dongle). If not, you can pick up an Ethernet to WiFi converter for under $40.