To do so if you don't know already
You make 3 sentences
the top sentence with 5 syllables
the middle sentence with 7 syllables
the bottom sentence with 5 syllables
an example would be:
Rapping at the door
Fills up agéd pillowcase
So sick of Smarties
It isn't hard really.
Get Creative and Discus

P.S. want some more info on haiku's check out wiki
http://en.wikipedia.org/wiki/Haiku