First, if your son or daughter was born in US and became a US citizen, he or she has to be at least 18 years old to invite or apply for you to get a Green Card. It means your son or daughter has to filled I-130 and I-864 form. Second, if your son or daughter is under 18 and live in the US, then he or she must go to school here. That means your child needs help from the parents--you can stay in the US because of your son/daughter is in school. (You can stay until your child graduate from high school). It means you are still not a residence here, but you can become a residence which takes a long time; again if your son is under 18-- you should go through lawyers. Any other questions, if I can provide, happy to share.