The standard for modifying child support orders is different whether your order was the result of an agreement or by a court order after a hearing or trial. You may resolve child support between yourselves with the assistance of experienced attorneys.
You need to file an action in Family Court to seek permission to relocate. You will need to show how the relocation is in the child's best interests and that the relationship between the child and non-relocating parent will be protected despite the move.
If you are able to work out the issues with your spouse, you or your husband can take a summary of your arrangement to an experienced attorney who will represent one of you and prepare the necessary paperwork. Once you get the paperwork from that attorney, the unrepresented party should then review it with an attorney before signing anything. It doesn't have to be expensive, but it's best that you both fully understand what you're agreeing to.