You have a couple of options. The easiest is to just let it ferment to dryness, add just enough sugar to carbonate it, and enjoy your sparkling cider dry. If you bottle before it's done fermenting, you'll need to stop fermentation in the bottle at just the right point, where it's carbonated, but still sweet.
You could use a hot water bath to pasteurize it, but if it carbs up unevenly, or you don't catch it in time, you could very easily end up with bottle bombs.