All OSM messages are created within the Message tab of OSM.  Messages can be created in three different ways.

1. Uploading a JPG

2. Created off a custom template

3. Created using WYSIWYG Template Designer (What You See is What You Get)

Choose the zone folder where you want to create the message. (Main, Side, or Banner)  Click the white paper with the green plus sign in the OSM task bar to create a new message.  You will then be prompted to choose from a list of templates available to you.  Choose a template and click next to create a message.

Messages can be edited after they are created.