You will most likely need a HMDI cable. Your laptop might have a micro HDMI.
Check out either of these:
http://www.bestbuy.com/site/insignia-6-hdmi-cable-black/4127007.p?id=1219096725673&skuId=4127007
http://www.bestbuy.com/site/insignia-4-high-speed-hdmi-to-mini-hdmi-cable-black/6186216.p?id=1219193668383&skuId=6186216
And as a last resort, you might even gave a Displayport connection on your Dell, so you can use on of these:
http://www.bestbuy.com/site/dynex-6-mini-displayport-to-hdmi-cable-black/8720139.p?id=1219361171271&skuId=8720139
Good luck!