For this image, I blended two seperate images to make one. One image was used on a slow shutter speed whilst the other on a faster shutter speed. 

I dragged one image over the other and used the overlay tool, I then masked the layers so that I could then use the brush tool to erase any parts that I didn't need. 

I then made the image black and white so that you can see the blurred parts. I added the slow shutter speed picture because it shows more movement. 

Final image. 1