If your TV does not have a digital receiver (all TVs built after a certain date had to have it, possible Jan 1, 2008?), then you will need a digital receiver box. They used to be about $40.
I don't really think cable TV is a must these days if you don't have to watch shows immediately after they air. If you're willing to wait, Netflix/Amazon Prime is a better deal than Hulu+. Of course, HBO shows aren't on those platforms. I just typically rent a copy from the library after the DVD/Blu-rays come out and watch the entire previous season in a week.