@Babbelbox: There is a SYNC button, and also a REC button on the bottom left side of the board. If you keep them both ticked, then the study should update for all members of that study and the new moves would be visible to all as well in the notation. The SYNC button keeps everyone on the same position, and the REC button records the moves to the server (i.e. updates for everyone rather than being done just for you). Your private study should have the "Enable Sync" option enabled on the main config page for the overall study in order to see both buttons.
As far as setting up positions for practice, you could go to a new chapter of your study -> Insert FEN/Board Editor -> In the Analysis Mode option: Practice with a Computer, or if you want to practice with a training partner, go to the lichess main page -> Tools -> Board Editor -> Insert FEN -> And then on the right hand side of the board there will be options with one being crossed swords where you can practice with either the computer or a friend.