Hi Jojo,
DING is a Southwest airline program. You sign up for it to be put onto your computer at southwest.com. You don't have to put in a local US zip code. I put in 90210 and it works fine. They asked us in the last year to add favouriite airports (to make your ding locations more concise) so I'm sure they do that now for new sign ups. Then your computer will "ding" when there is a special. Usually daily.
These specials just last for hours and they are usually SWs best prices. Southwest flies out of Buffalo for those in S. Ontario. Also, Albany for those in Eastern Ontario. Seattle has southwest. I'm not sure if any Maritmers use it. I guess Manchester, NH would the "closest" one. Southwest prices are a lot cheaper than our fares because the tax is so low.