Sneak is used to pass creatures stealthely w/o getting attacked(in most cases, aggroed)...it is required for some abilities to sneak and be behind or flanking your target.
Hope that helps
Here are the links to the forums and to forums newbie discussion.
http://eqiiforums.station.sony.com/eq2?no_redir=true for EQ2 forums
http://eqiiforums.station.sony.com/e...oard.id=Newbie for EQ2 "The Newbie Yard" in the forums