I spent a few years teaching math and I think that made public speaking rather easy for me. If you're looking for a supportive group to help improve your public speaking skills then I recommend you checkout your local toastmasters group. I've not attended myself, but I've heard from several members that it was life changing for them. Just like most every other group, they don't discriminate based on race or gender - so you should be very welcome.

If there's a technology you really like working with, then you might want to look on meetup.com to see if you can find some like minded people and look for an opportunity to present something. Some of the meetup.com groups discriminate based on gender or race, but the vast majority do not and are very welcoming :)