Sorry for the late response; I've been ignoring emails for a long while :) Anyway, por = for and para = for but what English speakers consider a single meaning, Spanish speakers consider two separate meanings (just like how they have estar and ser which both to me, as a native English speaker, are really the same thing). A native Spanish-speaking coworker described it as this to me:
Puedo trabajar por ti -- I can work for you (as an employee, with you as the boss) Puedo trabajar para ti -- I can work for you (in your place because you're requesting off)
So in English, you have to determine what you mean by "work for you" based on the context but in Spanish, there are two separate words for "for" which eliminate that ambiguity.
That being said, I'm not 100% sure I have my sentence meanings translated correctly. It's been a while since I practiced my Spanish and for all I know, I got the meanings reversed, so wait for some higher-level Spanish learners/speakers to comment before you repeat this!