sharing objects between classes and making hierarchy

There are four kinds of user types. Admin,Super Moderator, Moderator and Member. Admin can add and delete all kind of user types including admin and can add main topics but he can't upload documents and project. Super moderator can add moderator or member for the any created topic(s). The super moderators can upload and remove documents and projects. The projects have kinds like group project, individual project, deadline. However documents have types as well like pdf(book), ppt(slides), urls. The moderator can be a member in other topic(s) and can view projects related to the topic. Member can enroll the topics wanted and can add projects.

The issue is that here my lack of design oop concept. I can't make the hierarchy. I really don't want full code just need ways helping to solve the problem. As far as I can see here just is a relationship between moderator and member. I have programmed in C. But, I haven't been familiar with OOP yet. By the way, I comprehed the logic related to the problem, but I can't write in OOP concept yet. How can it be come up with a solution? I think I need the hierarchy. Lastly, there could be multiple data accessing because if a member created by admin, it should also be managed by super moderator and interface can be used because of adding and removing by admins and super moderators.