If you use GIMP instead of Photo Shop this thread might interest you.
I am a GIMP user. Most of the tutorials for photo processing (that are really good!) are mainly for Photo Shop. Sometimes we can get struggle trying to find similar function in GIMP, but most of the cases is easy.
I was writing the steps for GIMP when I found this link that can help us to process our photos.
I find it really helpful.
p.s. I will check them. If I find a missing tutorial (that I’ve applied) I will write down the steps and share it with you.