1. The rights on the file system.
 
    Rights             Owner User    Owner Group
    drwxr-xr-x   2 robert               robert                       4096 2008-07-26 11:44 Pictures
    drwxr-xr-x   2 robert               robert                       4096 2008-07-26 11:44 Public
 
    Owner user and Owner Group owns the file or folder.
 
    drwxrwxrwx, from left to right, it means
    (1). d : Dir
    (2). The first rwx(The owner's rights) : read right|write right| execute right
    (3). The second rwx(The user's rights in the same group) : read right|write right| execute right
    (4). The third rwx(Theuser's rights in other groups) : read right|write right| execute right
 
2. The previledges of the user.
     In ubuntu, you can add the previledges
     (1). System -> Administration -> Users and Groups
     (2). Select the Robert user, click the Properties , switch to the User Priviledges , and there you go.