Once you make that first sound, the rest is (fairly) easy. Ican only suggest trying as many combinations of lip position as you can, in hopes taht you find one that works. After that ... the pitch of the note depends on the length of the resonant cavity formed by the mouth; the length can be varied by moving the tongue: further forward to go higher, further back to go lower. Then it's just a matter of practice till you can hit the note you want every time.

I can whistle in the normal way, but I've never been able to whistle through my fingers. Mom can whistle, but only on the inward breath; I can do both, which means I can hold a note as long as you like,and I never have to pause for a breath.

If you whistle with a mic, don't get too cose, or it will upset the resonance andstop the whistle -- try bringing your hand close to your mouth and you'll see what I mean.

Steve