Groups and Roles and Users

Hi list,<br /><br />Could someone suggest me how to get a documentation about Groups and Roles and Users ?<br /><br
/>Itwould be nice to see a simple and easy documentation (a tutorial could be better, with pgadmin much better).<br
/><br/><br />Regards <br /> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-<br
/>                                  Atenciosamente(Sincerely)<br />                        Ezequias Rodrigues da
Rocha<br/> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- <br />A pior das democracias ainda
émelhor do que a melhor das ditaduras<br />The worst of democracies is still better than the better of dictatorships<br
/><ahref="http://ezequiasrocha.blogspot.com/">http://ezequiasrocha.blogspot.com/ </a>