I suggest your child to take the TOFEL J. test first. You can have more information to help you target more schools and we can provide with you the best recommendations of schools.
In terms of learning English, it is a long-term process, where your child needs to be exposed to on a continuous basis. We can provide a teacher who can teach your child English face-to-face or online. Also, let your child read more English books and watch more US TV.