The National Institute sponsors the National Institute of Mental Health (NIMH). At NIMH's site, all the major mental health diagnoses are listed and link to further information. Each category, for example Anxiety, tells about different types of anxiety, causes, signs and symptoms, who is at risk to have it, treatments, what it is like living with it, and clinical trials (research) you can participate in to help scientists learn more about the disorder.
NIMH's website is helpful for friends and family members who want to learn more about mental health.