Exercise Crane 1
1 Open crane.jpg from crane folder
2 Create New adjustment layer with Levels
Move middle triangle to the right observing changes of the crane's density
3 Create blank new layer
4 With black Brush Tool black out everything around the crane
5 Reduce opacity to about 10%
6 Use Healing Brush to fix the white spot on the grass (right bottom corner)
Summary:

To selectively darken some part of your image, you can create a blank new layer, paint desired area with black, and then reduce layer opacity to about 10%

Crane 2
1 Open crane2.jpg
2 With Magic Wand select entire background, Feather by 1 pixel (Select > Feather) and inverse selection (Select > Inverse)
3 Open background.jpg
4 Window > Arrange > Tile
5 With Move Tool drag crane into background image
6 Reduce size of the crane by command Edit > Free Transform (hold shift key while dragging)