The WP Message Board allows you to create multiple discussion "threads" for your teams (Planners and Helpers). Access to each thread can be configured to allow specific people to read, others to read and post, and others to not have access to it at all. Users with read access can subscribe to a discussion, which means they will be notified via email (and possibly text message - if configured) when a message is posted to that discussion.
Begin by clicking on the Message Board navigation link under the More tab once you've logged in to WP. Next, click the New Discussion link (top right). Fill in the form and click the Create Discussion button. To post your first message to the discussion, click on the discussion title, and post a message.
WP allows security level 3 Planners to set the minimum security level permitted to create new discussions. This setting can be modified on the Church Account Setting page (More tab > Organization Account > Account Settings).