The two most important pieces of information to share with your user base to promote your Challenge are 1. Shine's Download Link (shine.joulebug.com/download) and 2. Your organization's Access Code. These should be included and emphasized in all communication.
Other pieces of information to include are more specific to your Challenge, like the start date and any incentives being offered.
"Everyone get ready! Fun Sustainability Challenges are coming to Acme, Inc. We will be starting with an Earth Week Challenge on April 22nd! To participate, download the Shine app: shine.joulebug.com/download and use the ACCESS CODE: acme543. Then, join your department’s team in the Acme Earth Week Challenge. Log your sustainable Actions in the app to earn points for your team, and check out the awesome prizes in the Info Section of the Challenge"