Use the force on the wall panel on the left in the room where the droids are and use the blocks to make a platform. Now, on the right side of the room you will find two levers- pull these to get blocks to make into four buttons. These will control the platform you made. Move the platform to the upper left corner and doublejump from that into Threepio's cell. This will create enough weight to lower the floor and let both of you out. Do the same thing to get R2 out of his pen.