Erase the background of the tourist using the magic eraser tool
1) If the lighting does not match your background, try flipping your by choosing Image > Rotate > Flip Layer Horizontal
2) Next, you'll want to re-scale your image so that it fits your scene. You can do this with the "bounding box". Click the Move tool and then click Show Transform Box in the options bar for that tool. This will put a "bounding box" around your image and you can rescale it (drag the corners so that it doesn't stretch your image).
3) To create a shadow, you first need to create a selection in the shape of your image. You can easily do this by control-clicking the image thumbnail in the layers palette.
4) Then create a new empty layer by clicking on the new layer button, click on this new layer in the layers palette to activate it.
5) Then soften the edges of the selection using Select>Feather (Larger number will be softer edges)
6) Fill this selection with black (on your empty layer) by using Edit>Fill Selection
YOu must De-Select before moving on!
7) Move this layer around an you can see that it can be placed anywhere, but it doesn't look real yet
Adjust the stacking order of your layers to make sure your "shadow" layer is underneath your person
8) Change the opacity of this layer in the layers palette, and rearrange the layers so that the shadow layer is underneath the object layer.
10) Finally, distort the shadow using Image>Transform>Distort
Defringe your images