"She works for the gallery."
Translation:Ella trabaja para la galería.
I wrote the comment you replied to several months ago, and I just want to say, as encouragement, that eventually when to use para/por will become intuitive for you. I look at this sentence now and would know to use "para", even if I couldn't tell you exactly why. :)
I'm glad you figured it out, even if only intuitively!! I'm not really discouraged because I've realized that a big part of learning a language is persistence, especially when you're challenged by a new aspect of that language. Many of the words, sentences, and grammar that I used to struggle with months ago are now second nature, too. But thanks for the encouragement anyways :D