1. load your image double click on the lock in the layers pallet to unlock it as a background image, give it a name such as "bag".
2. duplicate this layer and name the new duplicate layer "popcorn"
3. use the polygonal lasso tool to outline the bag then click on elect then invert now click the delete key to cut out the bag
4. do the same with the popcorn layer this time cut out the popcorn and label.
5. create a blank layer at the bottom this will become the layer that you can place any background you want.
6. after you have placed your background picture ect. adjust the transparency of the bag layer.