Easy. Just remember you have to be Friends with someone in order to send them a message.
You can send messages to your friends from many places inside the Knockdown Outdoors app. You can send a message to a single person, or to a group.
1. Select In-Stand Chat from the main menu.
This will bring up a list of all your active conversations.
2. Press the + button at the bottom of the page.
This will start a new conversation. Click into the "To" field and add your desired friend(s). Then type your message in the "Enter Message" section and press the "Send" button.