M.I. Wijngaarde , Oct 18, 2006; 04:42 a.m.
I'm no expert but the hard part is that the images are not taken from the exact same position...However quick and dirty I gave it a try. I use the "layer mask" technique: first layer the dark image on top the light image which a added a layer mask on. Do a search in the forum on "layer mask" and "merging images" or so and you will find lot's of detailed descriptions.
quick and dirty