To start off, open an image you want to turn into an "artistic" piece of art. Im using the image you see on the left, if you want to follow the tutorial, you can download this image HERE

First thing you need to do is create a new layer, so simply go to Layer->New->Layer. Click OK on the dialog box and you should have a new layer.

Set your foreground color to white (press D to reset the color palletes, then press X to set foreground to white)

Now use the Paint Bucket tool to fill the new layer with white.

Now open your "History" pallete. If its not open, go to Windows->History

If you followed the tutorial correctly, you should now have the same history as mine tothe left.

Next, click on the empty box to the left of the "Open" item on the history pallete to mark the history brush.

Then in the Toolbox, select and hold down the History Brush, then select "Art History Brush"