Ok to begin, hit the "Q" key (or the Quick Mask panel again). Now make sure the brush is selected. Hitting the "X" key reverses the fore and aft colors: make sure the foreground color is the black one to select areas, or white to deselect areas, and start selecting the area you're going to get rid of.

If you hit the "Q" again, you'll see the area it's selected in the "marching ants."

Now, using different sized brushes to get large areas or tiny corners, select everything...

Then hit the "Q" key once again to see the selection, then hit "delete" to get rid of it. In the above example I had a blue layer underneath, to show you how the deleted area was made transparent.

After that all you've gotta do is slide an image in on a layer below, hit it with a motion blur filter, and voila, Charlie cruising through town...

Charlie cruising through the hills...

Charlie cruising through a park...

Charlie cruising out in the country...

Charlie cruising along a cobblestone street...

Charlie cruising across a castle moat...

Charlie cruising past Bobey's...

Charlie cruising at thirty-eight-thousand feet...