You can achieve your requirement creating these 4 roles through Sitefinity interface. You can assign permissions to each of your role for all pages, for certain pages or for the owner of the page. So that you can decide whether a role will have full or parital access.
We use ASP.NET Membership providers. You can use System.Web.Security
namespace that contains classes used to implement ASP.NET security in Web server applications or Telerik.Security namespace.
the Telerik team