Probably the first thing to do will be to conduct an online search with various community/group websites in your area. Depending on which city you live in, you may find an intimidating number of groups to join, or you may find that you'll have to drive out quite a ways to physically meet with a group. If you can narrow it down to a few groups--assuming you have a lot of choices--then write in to whoever it is that organizes the group and see if you can attend one of their meetings. That might involve you having to contribute something before being allowed to attend, or it might mean they simply welcome you and allow you to observe.
The important thing, however, is to make sure you're COMFORTABLE with how the group operates. If you find that the group is very competitive and takes "tough love" to the point of cruelty, and that's not your thing, bail. If you find that the group has one Svengali-like figure that everyone kow-tows to, and it means there's no dissension in the ranks at all, and largely exists to stoke that person's ego, bail. If you find that it's a group of supportive people that give useful, critical comments that actually push people to improve their writing, and the atmosphere is one of mutual respect and enthusiasm for improving as writers, hold onto that group with both hands and don't let go.
The problem with any writing group is, you won't really know whether it's a good fit for you or not, until you see the group in action. And the wrong writing group can be a horrible experience that sets a person's journey in the craft back years, or perhaps forever. The RIGHT writing group, on the other hand, can lift a person's writing to a level of Good they hadn't even known they could reach because they're getting good, useful feedback that shows them how to build on existing strengths, while eliminating weaknesses.
I guess it boils down to your own feelings when you attend. If you feel nervous, just because you're nervous about the new group, make the effort to endure that nervousness. But if you feel nervous, and even hurt because the group is just cruel and demeaning, back off FAST. Good luck.
