[xwiki-users] Some question about ACL

Hello, My xwiki use ldap authentication on "always authentificate" xwiki. How can I attribute a defaul group on new ldap users? I want to change some top menu entry based on the user group logged in. By example,  I don't want "Wiki index" or "Create Space entry" entry on top menu for my user in MyNiceGroup. Finally a friend found in xwik.com an example of some editorial group with ACL (in french) but I could not find it. any ideas? thxs for your help.