Replying to Replacing Brake Fluid?

I recently bought a 2010 Toyota Corolla, and after having it just a week or two a maintenance light turned on. I looked it up in the manual and it said either the whole system's fucked, or the car is just low on brake fluid. I'm assuming its just low on brake fluid since I just got it. (although sort of pissed they didn't know this?) I would bring it back to the dealer, except I'm at school until the end of this week, and I have to go meet with my host teacher for student teaching Rhursday.

I know absolutely nothing about cars, and have never replaced brake fluid. I looked it up online and it sounded confusing with the air getting in the lines and what not.


So my question is: As a total car n00b, is this something that I should attempt to do myself, or should I have a professional do it for me? Would it be expensive to have a professional do it? Or am I over thinking a simple task?

Thank you so much to anybody who helps.