How can you learn to see ghosts?

First, you need a TON of LSD. Then, just watch Twilight Zone and Scooby Doo reruns.

GHOSTS ARE NOT REAL!!!!!!!

As I know you are right- there are no ghosts; what we call ghosts are entities that are living in other dimension then ours - and they do exist; if you are asking how to see those entities, then you would need a lil practice, some exercises to open your 6 energy center and open your mind in a way of "releasing all fears" that deprive you of seeing what is beyond this level of vabration!