Measure the dimensions of the opening at the top of your plastic storage container. Subtract 1/2 inch from each and cut a piece that size out of the bottom of the drawer where you want to hide the extra compartment.
Install the concealable hinges into the side of the desk next to the secret door you've removed. You can do this with a small cordless drill. On the other side of the gap in the drawer from the hinges, glue a small piece of wood on the bottom of the drawer to keep the door from falling through when you close it.
Attach the magnet lock to the door, taking care to follow the manufacturer's instructions, as they will vary by company.
Use the super glue to attach the plastic storage container to the bottom of the drawer. Allow two or three hours to dry, and then close the door. Then slide the drawer into place.