the long post goes into the hole on the body of the foot or on the body of the needle arm...some machines do it one place, some the other. the funny looking little hook piece rides on the top of your quilt to gauge how far apart the rows of quilting would be. (the most common machine quilting for many years was the simple crosshatch). the round bar will be parallel to the machine bed and the hook will point up...have fun, i have a version of this in my treadle accessories...