You will need to have her tested through the school system. If you believe your child is gifted, the best course of action may be to contact the principal or counselor at her school. These people can get you in touch with the diagnostician who administers tests for your school.
When your child takes the aptitude tests at school, if he/she places high enough, someone from the education department in your county will come to the school to test your child. Mine was tested this way and entered into gifted classes when he scored the proper scores.