Hi Sandy,
No problemo, it's basically the same as the workflow
here.
Anyway, I use CCDStack to align the images and, more importantly, once aligned they can be normalised. This usually (though not always) fixes the colour cast in the background. First image.
I then colour combine the images according to the HST palette, i.e SII-Red, Ha-Green and OIII-Blue. Maybe tweak the exposure here with a bit of DDP, then save at 16 bit tiff file for export into Photoshop. In your case I also made a master luminance from addition of the three colour exposures using a maximum combine, again, saved this as 16 bit tiff for Photoshop.
Once both files are open in PS I then colour balance the RHS of the histogram of the colour image, usually this means knocking off some of the green intensity as Ha usually dominates NB nebula images (again, not always). The Luminance channel get a bit of sharpening of the image excluding the stars, standard fodder here, though sharpening is a personal preference, I like sharp images, so tend to over sharpen them according to most people 'round here.
Now, working with the colour image, bring up the Hue/Saturation adjustment and desaturate all the magenta, you can experiment with the range of magenta/violet to knock out, this removes the violet stars and halos from the image, but really screws the star colours, if you want proper coloured stars, then you should do a short exposure RGB imaging run for the stars. Virtually none of the nebula will be this colour, so knock it out completely. Image 2
Now, go through the selective colour regime listed in the website I referenced, I have made a PS action to do this automatically, this shifts the colour palette to the more "golden" hues and enhances the blues. Image 3
Combine this image with the luminance in the usual manner, the image will wash out the colours, so I use a couple of methods to bring those back. The first one involves duplicating the colour layer in PS, then converting it to a Multiply layer between the Luminance (Background) layer and the colour layer, you then vary the opacity value of this layer to get the desired effect. Or, you can use Louie Atalas' method of duplicating the LRGB image, changing the blend mode to Soft Light and then varying the opacity of this layer. I use a combination of both as I find that each works in a slightly different way. Image 4
Lastly, combine all the layers and save as a psd file and import into Lightroom, use the clarity and vibrance sliders to your own liking.
Hope this helps.
Cheers
Stuart