You can find the groups by clicking on the “hamburger menu” (those three lines next to your avatar at the upper right) and selecting groups. You can click on a group to see the group members. If you click on a user you’ll see their “user card”, (which you can click again to see their profile). There is a Message button on both the card and profile.
While Ning had the notion of public “Wall Posts,” both for Users and Groups, Discourse does not use this metaphor. For public messages, we recommend that you post a new topic on your group’s category.
In Discourse, a “group” is a collection of users, and a “category” is a collection of topics. We can use groups to control who has access to a category, but they are not the same thing as they are in Ning.
We will probably experience some growing pains with how groups work. One concern is being able to silence the categories that you don’t care about.