Cadets is a weekly Sunday event where master raiders Silver & Cara train people with the commonly used tactics for all raids currently available in game. These are the hard mode tactics that are usually used for guild raids, and will stand you in good stead for most pugging opportunities, and give you a solid basis for a raiding career.
Make sure to read Silver's full post about the Cadets as it explains everything you need to know:
thankfully its all sorted now this patch is acting so weird.
Ugh not sure if anyone else is having issues but game is now saying i'm no longer part of the guild i never left nor got kicked log alt and its saying i got kicked on that char but different guild