Contact your local Child Find office. Child Find is part of the Individuals with Disabilities Education Act (IDEA) and is a National Program. Get your child assessed, at no cost, to identify any disability. They connect you to your state's early intervention services from birth until the age of three. Services they connect you with may be anything from physical therapy (primarily to support gross motor skills) and occupational therapy (fine motor, sensory needs) to speech therapy.
Contact your local public school district if your child is at least three or near three years of age. Public school districts are not allowed to evaluate for autism spectrum disorders. With a proper diagnosis, either from IDEA or a private practitioner, the district works with you to create and Individual Education Plan, IEP, that identifies services the district provides. They provide speech and communication supports, occupational therapy, behavioral and sensory support as well as support for reading comprehension, hearing issues and educational strategies for attention problems.
Contact the school district even if your child is home schooled or in private school. Some related services that public schools have to provide at no cost to children may be provided even if a child is not enrolled.
Contact your insurance company, if you are insured. Many states have already enacted legislation that requires insurance companies to provide coverage for Applied Behavioral Analysis, or ABA. ABA is a method of providing and analyzing behavioral interventions and assessing their effectiveness.