The permission group can only be applied to "User" type user. The "User" is similar to an administrator but with fewer permissions, and this type of user can only log in to the Web version of your system.
To create a new user permission, click the "New permission group" button:
And apply the needed permissions.
Here are the permission levels:
"Forbid" - the user will not be able to see the lists of entries or menu items;
"Review" - the user will be allowed to view the entry information only;
"Create" - the user will be authorized to create and view entries;
"Modify" - the user will be authorized to create, review and edit entries.
"Archive" - the user will have all possible authorizations to create, review, edit and archive.