Thats it, You have it essentially correct. AWESOME JOB !! ... Of course there is probably some tweaking to do but it looks like you have combined the color channels successfully. Please let us know how you did it? Those jagged diagonal lines are there because I converted the images from FITS (an astronomy specific file format) to TIFFS in a demo program that places those line until you buy the product. This is great!
Thanks,
John Freeman