The thread mentioned above is:
but it appears to be blank when I try it.
1. If you want to know more in a cerebral sense, buy Winslow Yerxa's Harmonica For Dummies. It covers diatonic, but not chromatic harmonicas, and despite the title, is rather encyclopedic.
2. If you'd rather learn more intuitively (the way I did and the way most people did "back in the day"), play in the correct key (usually the same key for genres other than blues and cross harp as explained above for blues) and noodle around. If you relax, and not try too hard, you will get better and better. That said, some players want to be more scientific and plan it out. Depends on what you like.
3. Check out www.harmonicaspace.com. It is a relatively new site, but has a lot of members already, and a good mix of new and experienced people, including some famous players. I believe that several of the members give long-distance or in-person lessons.
4. If you want to listen to harmonica music, I'd suggest listening to the older stuff first, including Little Walter, etc. and then move chronologically.
5. While there is much to be learned in terms of harmonicas, mics, amps, effects, and techniques, harmonica is also about knowing when to not play, or hold a note, or pause. Perhaps it is even more true of harmonica than guitar.
I've played harmonica for many years, and now I'm fulfilling a dream by finally getting guitar. The guitar habit has rejuvenated my interest in harmonica and led me to finally start figuring out amplified harp.
Wow, lotta cool stuff on this thread. Years ago I got a copy of Klutz Books Learn to Play Blues Harmonica, stuck the harp in the car (long commute) and listened to the tape. Tell ya what, once you learn the shyoo-oowhee thing to do the bends, it's a blast.
...S'pose I really should pony up for a decent harp someday tho. I hate goin' to rehearsal on time...