By default Latest Posts are placed in Sidebar. In order to have latest Posts shown, you must have Portal option enabled in Admin Dashboard:
Home » Board Settings » Portal Settings
If you choose not to have Sidebar in Front Page, you will still have Latest Posts in Front Page Mobile view. For more info read the next item below.
NOTE: Dont’t panic if there is nothing to be shown in Latest Posts when first install MyBB and NetPen Theme, because you need at least one Thread/Post created so something could be shown there!