There's simply not enough data in the image file to get anything remotely like a reasonable image. The image can be made larger, with interpolation being used to 'fill the gaps', but it would be far from ideal.
To give it a try, he'll need something like Irfanview. (It's free and deserves a place on everyone's PC):
http://www.irfanview.com/
Open the image in Irfanview, then go to Image > Resize/Resample ans select one of the larger options in the right-hand panel. Then a bit of experimentation might be needed, using some of other options from the 'Image' menu (such as 'Enhance Colours'). Then go to File > Save As to save the image with a new file name. (I'd normally recommend ensuring that the file type is set to JPG but it might be worth trying BMP, to avoid data loss in the compression).
It would be far easier though, to do a Google Image search for 'lightening' and then select the 'large' filter from the left-hand side.There are hundreds of stunning images available.
Chris