When you log in to the app, you will be taken to your Latest Posts page. You can also access this page at any time by clicking the navigation button and then selecting Latest Posts. This page will show all Posts to your groups as well as those sent to Communities that you follow.
You can easily filter these Posts by clicking "All Posts" at the top center of your screen, to filter posts by Assignments, Polls, or Quizzes.
To see Posts from a certain Group you will need to click the navigation button, then Groups, and then select a Group to view all Posts sent to that specific Group.