My first attempt to write a tutorial about something.
My result: [link]
Feel free to comment on this very first try
The screenshots in this tutorial are made of the german version of The Gimp. I hope, they'll help anyway.
The downloadable zip-file contains the tutorial as a html file and the screenshots for the html file. Just unzip and use.
Inserting all pictures in layers the easy way:
Open The Gimp. Open the folder with the pictures.
Drag + Drop the darkest picture on The Gimp.
As the picture is open, Drag + Drop all other pictures
in the right order (ascending to the brightest one)
on the dark picture. Each is automaticly placed in a
new layer. Thanks, The Gimp!
(This really saved me tons of time as I discovered it