You can't magickally change genders. Doesn't work that way. You can go have cosmetic surgery though. Physically transformation is not possible. Sorry but you're stuck with the gender the powers that be gave you. ^_^
Taken From my SoM Survival Guide 1.0 Post in the comments forum:
People need to understand two important things about magic and spells:
First, Magic and/or spells are not the solution to every problem - in fact sometimes doing nothing is the best remedy. Magic is neither good or evil, white or black or any color for that matter but is rather defined by the wielder and his or her intentions, though intentions may be great it is the results that truly matter
Secondly, magic and/or Spells cannot change your shape, weight, height, size, skin color, gender, sexual orientation etc.