Problems with your project:
1, The Box uses the Physics behaviour, Mario uses the platform behaviour.
Objects that use physics only interact with other objects that use Physics.
2, Your Mario Sprite is too big ( I think it it was about 400x300 scaled down to its current size) and the box is only about 70 x 60)
You really need to spend a few hours reading through the manual, or doing some of the tutorials!
See Kyatric's post (above) for some links.