If your TV does not have the ability to receive ATSC signals (look for this acronym in the TV's manual), then you'll need a converter box like any of the ones from this list:
http://en.wikipedia.org/wiki/Comparison_of_CECB_units
The "
Coupon Eligible Converter Boxes" do the work of tuning to digital TV signals and converting them to a format (like composite video, S-Video, RF channel 3, etc.) that can be fed into your TV like you would connect a VCR.
Millions of these boxes were made around the time of the US transition to digital television (June 12, 2009). Now that the transition is over in the US, there are not as many places selling these boxes, but you should still be able to some. The Canadian transition to digital TV is scheduled for August 31, 2011.