I have been working on a guide dealing with astro imaging and processing. The linked page is the beginning to that guide. I am providing it, along with videos and updates for free currently, but if you wish to donate to support this type of content, please fell free.
Note, this guide is not definitive in any way but more for those who are new to astrophotography and looking to get an understanding of processing and even what needs to go into imaging itself.
Astrophotography Processing Theory