Train

Open the train picture first in a new document. 

Then copy the Jennifer Aniston picture into it.

Move it to the right as shown below...

With the Jennifer picture layer selected, go to Properties... click on the Filters '+' button and choose Hue/Saturation (under Adjust Color)...

Reduce the saturation -drag the slider to the left a bit.

Add a mask to Jen's layer.

Select the Brush tool, increasing the brush size a lot, with a soft edge.

Start brushing over the part of the picture we want to hide.

When you're done, you'll have something like this...