New Ghost

I've been at Athena High long enough to know a few regular ghosts who wander the halls, a couple who like to posses computers, and about a dozen who simply sit in classrooms and stare at the students. For some reason I have never seen a single ghost in the library, which is why it quickly became my school sanctuary. 

To be honest, I have never seen this ghost in general before. I quickly distinguished her as a female because of her features. She looked so lonely, sitting there on the couch staring into the outside world. I bet she hadn't seen her family in years before she died. I felt sorry for her. I wondered why she ended up in the hospital in the first place. 

Suddenly, the girl turned and stared at me right in the eye. I froze. Her eyes where nothing but empty whites. Her gaze was cold, empty, and... sad. 

I wasn't exactly sure what to do, until she got up from her seat, walked to the wall, and through it.

I've never been so curious about the psychiatric hospital until then. 

Hoooo boy. This was easy... more or less. Anyway, I'm not exactly sure where I'm going to go with this story. I'm sort of just thinking or the setting, characters, and other basic information. I haven't even thought of the main character name, or gender for that matter.

Anyway, this is where I need help. I need you guys to come up with character info (or any other story info) if you can do that, it will be a huge help for me.

Thanks guys!