[otrs] How to use the roles

Dears, I have been trying to understand how can I use the roles in OTRS. I'm not being able to understand the example from admin guide. Somebody can help me with some real situation? Thanks! Camilo Vieira * Coordenador de Infra-estrutura de redes Navita http://www.navita.com.br/ * Portais http://www.navitaportal.com/ e BlackBerry http://www.blackberrycorporativo.com.br/ * 55 11 3055-2001