Congratulations on your CAG. That is so amazing and wonderful that you gave an unwanted bird a home.

Good for you!
Even though she is 16 she is new to your household so you are going to have to start from square one.
Michael's Basics of Parrot Taming and Training - The Complete Step by Step Guide for BeginnersI see by your profile you own four birds so you may not be a beginner but that article is the best place to start as far as taming a new bird.
When you say she won't let you go near her, do you mean she's aggressive or afraid? What kind of body language is she displaying? How close does she let you get before she starts displaying this body language?
There is a section in that blog post I linked called "Approaching the Cage" and that may be where you need to start.
Older, re-homed parrots can have special needs. I have a rescue bird and a re-homed bird and I bought a book called
"The Second Hand Parrot" and found it to be very useful.
