Open the locked door and chest:
In the Gryffndor common room find all the lost items untill you find
the Key (first floor, behind the statue). You must then use the Key to unlock
a door on the 6th floor as well as the locked chest in the studies area.
Secret Cards and Beans:
Cast the Glacius spell on every fireplace with Hermione. Everytime
you do so a Wizard Card will appear. You must also use Hermione and buy the
Snufflifores Spellbook from the Weasley twins. The book will teach you how to
turn flying books into mice. Everytime you turn a book into a mouse the mouse
will run into a hole in the room and a Wizard Card or bean will pop out.