All there is to using the built-in tuner is connect a decent UHF antenna to it. Then do an auto-program on your TV searching for digital channels. That’s it.
Don’t spend extra money on an antenna that says “HD” because all the HD channels are being broadcast digitally on the UHF frequencies. Go with a roof antenna if you can.
I’ve got a small indoor antenna, and only get 5 HD channels right now (since Fox is one of them, I’ve already got 95% of the content I want, at no cost), but they do come in either 720P or 1080i, and they look great when true HD content is being broadcast (NFL football on Fox looks great, as does all the stuff they broadcast on PBS.)
Actually, I should go pick up some coax and move my antenna up to the attic and see if I can pick up the rest of the locals.