You can start by going to your doctor. You can also start directly by contacting a psychologist for an assessment. You don't want to wait too long. It is hard to find therapists who believe in treating asperger's or autism-related problems directly if you didn't have the diagnosis as a child (at least before age 18) and legally, those disorders have to be diagnosed before age 18 to be entitled to government benefits for them as a disability or accommodations. Any therapist can help you with coping with the challenges in your life, whether those are related to asperger's or something else.