am traveling to brazil with my 2 week old what documents will she need?

She will need her own passport. no matter what age everyone needs a passport to enter another Country

She must have a valid passport and depending on where are you from a visa but most of the countries do not need a vise to enter Brazil

She will need her own passport. Some countries still allow parents to put their children's pictures in theirs' but there are fewer and fewer who allow this.

You didn't say where you were but if she's American, here is the relevant sit to visit;

http://travel.state.gov/passport/get/minors/minors_834.html

I have to admit that at 2 weeks, you don't have a lot of time. You may need expedited services and have to pay a bit more. Also, on a personal note, it's not that easy to get a newborn photo which conforms to their requirements. Using a bouncey seat with a white sheet works best. The eyes have to be open and both ears showing.

I'm a former Flight Attendant and I fly a lot with my three kids. About 8 years ago, I wrote an article on flying with children, which is totally non-commercial, which you might find useful. Most of what is on the web on this subject is written by people with no direct experience working for the airlines. My contact info is at the end.
http://flyingwithchildren.blogspot.com

Good luck!