You can either pay someone for a board (FE does this) that requires minimal know-how on your part. Or, you can use a free board that needs a bit more technical know-how to get set up and running. Even more know-how if you want to alter it any to suit any sort of particular look or need.
This board software is free, but you do have to have a place to host it (can be got for less than $20 per month) and someone who knows enough about web applications to install it and have it set up. Given that you've asked the question, I'm guessing you wouldn't know enough personally to set it up yourself.
My recommendation: for what you've described, it would be much easier to simply collect the email addresses of those in your church and send messages out in that manner. You can even use the BCC function to keep email addresses private.