If you're using the kit supplied chain it's a good bet that it is #415, basically a metric version of our #41 chain. Some kits I've seen have come with a smaller, BMX style, closer in size to bicycle chain. Use the search feature at the top of the page, type in 'chain size' and you'll have plenty to read on the subject.
As for sprocket size, follow the advice given to you above by Venice.
Tom