Oh it's easy.
Three lines: 1 - maximum 5 syllables, 2- max 7, 3 - max 5
If you can, get some sort of break in between two of the lines, so that the poem is not one 17 syllable sentence.
Say something about the provided photo.
That's it!
More explanation of the qualities of a master haiku are in the contest post, and it's helpful to have read it, but none of the characteristics are required as I understand it.
The bold 3/5/3 poem is my entry. All that stuff underneath is just what I did to get there. You don't have to post that, just the haiku is what most people do. Some folks tell a story about how they wrote it, or what it means or what they tried to do, but usually not. Read the other entries. It's a broad bunch.