There definitely is a trick to it - #1 being don't try to blow too hard and cup your tongue behind it - - I found this link hilarious and helpful!http://www.tagalongprairie.com/whistle.shtml-maggie
Thanks Maggie!I finally figured it out. Sheesh. I can now whistle twinkle, twinkle, little star. I think that is the song you are supposed to learn in order to whistle good. I just decided to try it, and it worked. Super hard though! Still going to be awhile before I actually use it with commands for Seek. I have to be good enough to hit the same notes each time... which I almost have for "come" and "that'll do"