Not too happy with you using autism to call someone dumb, but I'll leave this up assuming it was just a one-off.
Definition of sash for Students. 1  1 : a frame for a pane of glass in a door or window. 2  2 : the movable part of a window.
Drape the ribbon over the sash wearer's shoulder, with the lettering side on the front of the wearer's body. Pull the sash to the opposite side of the body and pin it in place, near the wearer's hips.