We are here to help you, but you have to help us. What's the model number? All new TVs have a built in digital tuner. Only specialty models for high end applications will go with no tuner, like for custom installs.
Somewhere on your TV (or separate media box if it's a hyper thin TV) there is a coaxial input, the screw type. You can plug basic cable in there. And if you are in the USA, there's a bonus. By law all cable companies must transmit 'in the clear' (not scrambled) HD signals for the local stations like Fox, NBC, CBS, PBS, CW, and usually a handful of others. In most markets, people get between 8 and 12 HD stations.
If you have a cable box and only pay for basic cable, then you lose that because the law says it only needs to be transmitted, not decoded or anything else. All TVs currently ship with a ATSC tuner for grabbing signal with a antenna. And a 'clear QAM' tuner for cable.
Just connect, and use the scan function in your menu, the TV will find everything. If your TV really does not have a built in tuner, which I find hard to believe, return it. TVs with no tuner are usually referred to as monitors, did you buy a monitor?