well skrying is, don't know about crystals on a map might need a bit more explanation. normally, you take a reflective surface [black mirror, bowl of water, crystal/crystal ball] and stare into it.
first of course you need to meditate and clear your mind, when you feel ready, stare past your reflection and try to focus on one question [if you have one. nothing if you just want to skry] eventually, images should appear in the crystal.
so yes, skrying is real, but i've never heard of putting it on a map. it should still work, just make sure the map isn't interfering with you seeing images. normally you should use a single coloured background.