We want someone who can provide the sound system and operate it for our Program. Where should I start?

Answer 1

If you are a registered nonprofit organization and in the USA, you can use VolunteerMatch (http://www.volunteermatch.org) to recruit this specific volunteer. No matter where you are, you can use IdeaList (http://www.idealist.org) and probably CraigsList (http://www.craigslist.com) to recruit this volunteer.

Also try posting something on your program/organization's web site regarding this need/opportunity, as well as any newsletter/bulletin you produce.