What can I do for nightmares and post traumatic stress disorder?

Talk therapy & meds. The primary treatment for ptsd is psychotherapy (talk therapy). Specifically, trauma focused cbt and emdr have shown effectiveness. As your overall ptsd symptoms improve, your nightmares should as well. Sometimes, a medication can be helpful in suppressing dream sleep or reducing the fear and anxiety that leads to nightmares. In this situation, it may be best to see a psychiatrist for treatment.
Nightmares. You already received an excellent response. So i will deal with only one issue - that of nightmares / sleep problems. Extremely good sleep hygiene is needed. Prazosin (minnipress) has been shown to work well when used off-label for insomnia & nightmares. Buspar (buspirone) + melatonin is effective for some. Many patients at military treatment facilities & vamc's receive acupuncture to help with sleep.
PTSD. Find a licensed mental health practitioner who specializes in ptsd. He or she may want to refer you for a psychiatric consultation for medication. You must deal with your ptsd as, left untreated, it can last forever and be extremely debilitating.