You have to find a pair of identic images and clear the entire game field. If there are wooden boxes on the field you can destroy them by clearing neighbouring tiles, the blocks made of steel can only be moved around but not destroyed. The objects can be connected only if there are no obstacles between them.
Find the same images and connect them if the way between them is clear. Note that you can guide the object both clicking on the very object and on the tile next to it.