I have been teaching Photoshop at a Photographic Art Centre (Photoaccess) in Canberra since 2002, Lightroom since 2007, plus some astrophotography processing workshops. Since moving out to the Central West, I only teach a Nightscape Course which I can teach with a combination of zoom sessions and a face to face night shoot around Boorowa in between Young and Canberra.
So you want somebody to prepare a free online bespoke tutorial in a specialised area like astrophotography, teaching you more advanced concepts like layers and masking while catering perfectly to your lack of basic knowledge?
It doesn't exist.
It is hard enough teaching the basics to beginners face to face when you can help people directly. There are so many variables that need to be sorted on the spot. One person might be able to post a link, but someone else won't find it adequate.
My advice is: - first enrol in non-astrophotography, face to face, beginner level Photoshop and Lightroom workshops, become proficient, THEN, do the free online tutorials that assume a basic level of knowledge.
Cheers
Joe