For many the biggest stumbling block to learning articulated whistle language (Silbo canario, among others) is actually managing to produce the strident whistle necessary to then learn to form words and sentences.
Please let me know if this explanation and demonstration is helpful.
Anybody wishing to learn Whistle Language (Silbo) can find me on Italki, an excellent online platform for learning languages:
www.italki.com

Silbo canario.
Silbo gomero.
Silbo herreño.