Perhaps you’ll find something useful here:
It’s not too late to turn back… 
But if you want to go further, here’s one of the best sources of information for beginners that I know:
Welcome dwest! Now you say you have a low D whistle? Most people in general have started out and recommend to begin with a high D. Most Irish music is set in the key of D, and since the high D is realitivly small, it’s easier to master the different fingerings. I’ve never tried a low D, but I’ve heard others comment that the large finger spacings make it a challenge to play. You may want to consider getting a high D, they are easy to come by and are inexpensive.
Good luck! 
we’re going to want to hear progress reports. we’ve been there too. keep at it, it’s worth it.
Start by learning the high D whistle. I beg you.
welcome! it looks for in google piles of pages to learn. whistletutor.com is a good one.
If you’re to buy just one CD of Irish music, this is it: http://chiffboard.mati.ca/viewtopic.php?t=29948&start=45
I recommend the Fliuit Tutor book. It’s for flutes, but you can learn these tunes anyway and they are easy tunes that are fun to play. I’m learning them on my high D whistle, and then after I’ve got them down I pick up my Bb fife and play them. My flute’s in the shop.
Gee…Dale never begged ME to learn on a high D! (Of course, when I began whistling, I didn"t know about C&F.)
So, I mostly learned on a Low F. Twernt easy. If I had it to do again, I’d listen to the advice given by others, and use a high D.
But, I’d wear earplugs, and practice OUT OF EARSHOT of neighbors, and any loved ones!
I now play only Lows, and love’em. But I’m a sad and haunted fellow, who’s prone to put on airs…
so, how’s it going now?
That’s funny - many people have begged me to STOP playing both low and high D whistle. Oh well. All this stuff is so subjective, so I’ll just venture my own opinion/experience.
Playing other than ITM on whistle from the beginning, is well, like using a gun to hammer nails. (Retreating behind barrier). It just seems like these whistles are so made for ITM. Also, you may find it easier to manage the rhythmic wonder of this music on the high whistle at first.
And BTW, don’t cheat yourself, ITM is not just some category - it’s a seemingly unending diverse joy…
Just my limited thoughts.
Welcome.
Philo
Hello,
I suggest “The Low Whistle” by Hannigan and Ledsam. It includes a CD and takes you step by step.
I find it interesting that the people most vehement about your starting on a high D have never played a low D. Read, they do not know what they are talking about.
Apart from have identical fingering, the Low D is a different animal. Go for it! Blow off the negativity! I did it and you can do it. In fact, learning the low whistle first made it much easier to learn the high D and the Irish Flute. Best, Cyril.
i play the whistle and flute for all kinds of music except itm. most times they work, some times they don’t. i also play them in small groups and again, most times they work, some times they don’t. a person got to blend. nothing against itm, i’ve just been exposed to so little of it and it all sounds the same to me, same with bluegrass.
be thankful for the drought here or i would have lobbed a few tomatoes over the barrier at you philo. lobbed them with a gun, i would have.