I second Bowditch.

CelNav is can be difficult. I've had classes on it and know the theory, but putting that theory into practice is the hard part. The instructors don't tell you just how hard it is to aquire and maintain a sextant sighting on a pitching deck, when all the stars look nearly the same through the sight (you get tunnel vision and can lose the constellation).

Truely accurate Celestial Fixes require a perfect horizon, so anywhere other than the sea makes that difficult. Also, light pollution from cities, trees, and whathave you can all block the sky and make fixes that much harder. It's sad, but these days a lot of mariners just use GPS and have lost the art and science of CelNav because the electronic gizmos are faster, easier, and more accurate. I just hope an EMP or something won't render the world's maritime fleets useless.

If you are serious, PRACTICE, PRACTICE, PRACTICE. It requires a lot of gear that Night Hiker mentioned.

All that being said, I wouldn't get discouraged. CelNav is awesome and really cool to know. It would be great in a pinch, and the ladies like it when you can sit there and point out stars and constellations.

Matt