I have to disagree with John on two points here:
1 - The English haiku should be under 17 syllables, but doesn't need to conform to the Japanese syllable count 5-7-5. Japanese and English are different languages, with different syntax. Pronouns and prepositional phrases in Japanese are optional in a way they couldn't be in English. Pronunciation also differs. For example, there are no diphthongs in Japanese, long vowels are formed by an additional vowel character (and therefore an additional syllable).
Follow the HSA link below, then go to the collections to see modern haiku in the English language.
2 - The haiku is written by the juxtaposition of two fragments. The Japanese haiku consists of a) the
kigo, i.e. a reference to season and/or time a day in the first or third line, and a two-line observation. Both the traditional Japanese haiku and the HSA make no distinction between haiku and senryu, as humans are considered to be part of nature. What matters in a haiku is the presentation of a concrete, real visual. Personification and abstract language do not belong to the haiku. The second link below is a great source of information on the haiku writing techniques.
Here are some links that should be helpful:
http://www.hsa-haiku.org/ http://www.ahapoetry.com/haiartjr.htm