There are a number of ways you can plug a computer into a larger screen. You can use HDMI or VGA cables to do so or even connect through wifi.
Here's a site that walks you though the steps, and gets you to identify the kind of computer and TV you are using, and suggests ways to connect the two:
Here's an article you can look through to identify the kind of connections you have on your computer and TV.
Here is a video explaining some of the basics of how to connect your computer to your TV.
The solution we like here in the office is an Apple TV and a laptop with OSX Mavericks installed on it using a feature called AirPlay
Apple TV: http://www.apple.com/ca/appletv/
If you are on a PC or Google device, you can use a technology called Chromecast to watch content from your computer/phone/tablet on your TV
Read more here: https://support.google.com/chromecast/answer/6006232?hl=en-CA