If you want a book or dvd to help you get started, a good place to look is The Button Box. Because they deal solely in concertinas and accordions, you don’t have to wade through a lot of guitar books to get to something helpful, and they cheerfully ship all over the world. [Full disclosure: The Button Box is responsible for this site. But it truly is a good place to shop for concertinas, accordions, and related items.]
If you’re interested in finding a teacher, don’t despair–they do exist and often teach by Skype, so location is relevant only insofar as it affects your internet connection.
Especially during the summer, check out music camps that offer concertina and/or accordion instruction. You also might find weekend workshops, which could be any time of year.
If you go to the Northeast Squeeze-In, you are guaranteed to find players at many levels who will welcome you with warmth and share playing tips with generosity.
If you’re interested in a particular genre of music, you can try to find sessions in your area, but beware of uptempo sessions if you’re a beginner. Slower-paced jams might be harder to find, as they’re more likely to be at someone’s house or a room at a community center than at the local pub, but unearthing one that’s a good fit will be worth the effort. Social music can be a rewarding way to learn, plus it provides an incentive to practice, should you need one.
If you can’t find a session but you know other people who like the same kind of music and play an instrument–or wish they did–consider starting your own group. Really, all you need is a room, a few chairs, and a free evening.

Piano accordion and fiddle duet on the porch. Photo courtesy of Stewart Dean.

Is your bellows bigger than mine? Photo courtesy of Stewart Dean.
This site brought to you courtesy of The Button Box, Inc.