Start slowly and gain her trust. Ask if you can clean stalls and help with what is needed around the barn, and tell lher that you are available to help on competition days to get horses saddled, etc.
Be prepared to do a lot of ground work and give alot of time. During that period, pay attention to how she moves around the horses, how she rides, disciplines, etc.
Trainers are very busy, so don't have alot of time to explain - like cleaning with a toddler, it's often easiest to send them away so you can get the job done. But, if you are watching and learning and there when she needs you, she may be very happy to have you there...
Good luck with your goals :)
There is no passion to be found playing small - in settling for a life that is less than the one you are capable of living. - Nelson Mandela