Do some research

Are there other groups or organizations you can get involved in?  If there are, find a local chapter and attend a meeting.  Introduce yourself to the organizers and let them know you want to get more actively involved.

If there isn’t a local chapter find out how you can create one.  With some of the larger organizations, you might need to be a little persistent.  Don’t take it personally.  Many organizations are short staffed and may not have the resources to get back to you right away.