I've moved this thread to Art, Literature, and Music. Please be sure to post your threads in the correct forum next time. Thank you.
To be honest I don't know if this is the best place for this question either, but the resource section is for sharing resources, not talking about how to make them. I think General Discussion would have worked too. Possibly Program and Utility discussion, though what your asking about is a little broader in scope than just what program to use.
I'm currently using Pyxel Edit, GIMP, and Krita when I make tiles. Not all at once, I use different programs depending on what I'm making. The version of Pyxel Edit I use is not free, but it is cheap and if you're doing pixel tiles it is worth much more than the asking price. There is an earlier version available for free but it is missing a few things and is very buggy. Still very much worth using anyway, just be sure to save often. GIMP and Krita are both free. GIMP is a good editing program, good for arranging tiles and adjusting hues and such. I personally find it difficult to work with so I don't do any creation in that program. Krita is a painting program. It's got a canvas wrap feature that makes it much, much easier to make seamless repeating tiles. I'm still getting used to it. I mostly use pixel art to do my work and Krita isn't suited for it.
I use Clip Studio Paint for character art, but it is not free. Krita will work well in this situation.
I use Pyxel Edit to create my sprite and other pixel animation, but the free version won't work in this case. Before that I used Graphics Gale. There's a free version and a pay version but the free version works just fine.
Krita will be exactly what you need to make backgrounds. It was made for stuff like that.
I don't think you'll have to get Photoshop at all. It's been losing footing as an industry standard, and depending on what you want to create you may find a better program in the cheaper options.