The Sisterhood is dedicated to the advancement of humanity by any means necessary. By being selected as a Acolyte you have the opportunity to become far more than you once were. The regimen of a Sister is strict and unyielding, but the rewards are great.
To join the ranks of the Sisterhood as an Acolyte go to Wallach, venture 4w, then 'enter' the Headquarters.
Advanced knowledge of the Gesserit Order is available only to those who have proven themselves worthy. Ask a Mother Superior or Proctor Superior in game.