The question is if you really want to use the Paper UI for controlling your system - the control part of the UI isn’t really feature rich yet and the Classic UI (resp. the native clients) are imho much more usable (as they use the sitemaps).
But if you really want to make your items appear on the PaperUI, it is fairly simple: Simply add to them a Group Item that has the tag “home-group”, e.g. the Group Item “Garden” from https://github.com/openhab/openhab2/blob/master/distribution/openhabhome/conf/items/demo.items#L4.
