Right Now Media
Go to https://www.rightnowmedia.org/Launch/Churches. Scroll down to where you see the FREE RESOURCES. Use the LAUNCH EMAIL piece as a starter for verbiage for the announcement. Watch some examples of how to make the announcement further down the page. This really helps to craft or mold the announcement for the context and culture of your network. You can also find artwork, banners, flyers, and power point slides that might help as well.