I recently found out my friend has a mental disorder and I'm not sure what to think about it. I'm looking for information on how I can help her!
Was she properly diagnosed by a professional? Such disorders need to be diagnosed by a mental health professional.
Yes, she was. What do you think causes people to experience mental disorders?
Sadly, the cause of having a mental disorder are sometimes unclear. There are so many factors involved.
Oh, I see. What are some treatments for mental disorders? 
The first step would be to get an assessment done somewhere like a psychiatric hospital by a psychiatrist, psychologist and/or a clnical social worker. There are psychometric tests that can be done, or simple observation and questioning.
I really hope she gets the help she needs! Maybe for now, I'll just make sure that I'm there for her if she needs me.
Absolutely! It's always good to have someone to talk to. Just know that it may not be permanent either, some features of mental disorder can be persistent, others relapsing and remitting and some even in a single episode.