You need to change the screen resolution settings in Windows.
1. Open Screen Resolution by clicking the Start button Picture of the Start button, clicking Control Panel, and then, under Appearance and Personalization, clicking Adjust screen resolution.
2. Click the Resolution drop-down list, and move the slider to choose a different resolution.
Most HDTV sets use the 16:9 widescreen format, so you'll want to choose a screen resolution where the shape of the picture matches the wide format of your HDTV.
3. When you find a screen resolution that looks right, click Apply.
4. If the new screen resolution looks correct, click Keep changes, and then click OK.
I hope this helps!
Windows Outreach Team