Don't know colorado labor laws; but in my state you cannot work part time until your 16 years of age, while most stores require 18. That being said, look for being a paper bob for a local newspaper; you are allowed to do that, at least in my state. But truth be told, any job at your age really is not going to be worth the time, they just pay to low.
If you really want to help your family, put all your energy into your education. If you score a 4.0, i am sure it will "help" your parents much more then an extra 200 dollars. This will not only reduce stress on your parents; because they can feel confident that you are excelling well in your education. But if you can even score a small scholarship it will take a huge load off the finical burden that comes with college. Not to mention a strong education will pay much higher dividends in the future; as opposed to working part time/full time at marginal wages.
Now if your already a good student (4.0+), then ignore my 2nd paragraph.