Access rights in EPiServer CMS have two dimensions. Partially that an individual/group has access rights to different modes in EPiServer CMS and partially that one can have access rights to do different things within the structure of the website. In general, the contents structure is used as the basis for setting access rights for who may do what. It is a great advantage if you plan your structure before you start to assign access rights to the contents of EPiServer CMS..
It is usual to build up access rights based on different groups and not on individuals. It is the group that has specific access rights, the individuals are only members of different groups. A group is created for each specific place (page) in the structure where the access rights must differ from other pages. There are also different groups for if one wishes to have different roles for editors within a certain structure. It is technically possible to give specific access rights to individuals but in practice it is more complicated to administer.