at 14 she should be in 9th grade and starting HS ball. the HS should get her into weight training , if she hasnt already. Even before season has started its OK to go ask for instruction in weights, etc. A coach would be a fool to turn down that request.
My 14 yr old does squats, deadlifts, clean & jerk for her "core" . In a couple of months, the difference is amazing in thier musculature.