Your strategy for finding an amateur soccer team to join may depend on your boldness. It's not hard to find a game going on in any park -- there's almost always a match in Sara Roosevelt Park or McCarren Park -- and if you're willing to approach a member of one of the teams, you'll probably be able to join, assuming you have the requisite skills. If you have trouble with this approach, your next best option is social networking.
Visit a site like MeetUp, which many athletes use to find teammates and games in cities; you can join an online NYC soccer group and stay posted on the latest games in your neighborhood. Alternately, you can use more general networking sites like Facebook or Twitter to seek out friends and groups in the city into which you might fit; further, if you have friends on these sites that share your interest in soccer, there's a good chance they already belong to an amateur team and can set you right up! With a little bit of ingenuity and sweat, you'll be back out on the soccer pitch in no time at all.