Must they include words? Other than a title?
Yes! That's the 'essay' part, to put some context, explanation, story, around the photographs. Not just a plonked-up short gallery perhaps, but something to read and contemplate or provoke interest or thoughts. A magazine style entry, or a travelogue perhaps. Well... these are my ideas anyway.
how do I do to post more pictures like you did with yours? I'm only allowed 3 pics per post...Since it's a Photo Essay would be easier if we could post more than 3 pictures at once... 
Indeed! You should use the 'in line' style of photograph presentation. Instead of the conventional forum 3x max up-loaded photographs (as most do for simple uploads). 'In line' style requires you to use an image hosting service (such as Flickr), grab the image URL and embed it in line with the text flow (not just tagged on the end like forum uploads). When composing a post, the little button with the landscape photograph above
auto embeds this.
I have set up a dummy Fickle account to do just this. It is free, can host up to 200 photographs, and even has a nice <Capture URL> button to allow just this. Photographs uploaded to Fickle can still be linked (and show up here), but you cannot see them on your own Fickle page. Photobucket, and others also have a similar linking function. Set the image size to 750 pixels before upload, and you will get the full page width displayed if you use <Large Size> on Fickle in this case.
A simple example perhaps:
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed sit amet risus sit amet tortor ullamcorper semper quis fringilla sem. Vivamus vel tristique risus. Etiam aliquet libero in orci iaculis molestie. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.
[ img]insert image URL from Fickle [/img]
Nam scelerisque risus in mauris scelerisque nec varius tortor vestibulum. Suspendisse in velit enim. Fusce dapibus condimentum mauris. Mauris nec risus dui. Vestibulum eu sapien nec nulla posuere fermentum. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos.
[ img]insert image URL from Fickle [/img]
Phasellus ultrices ornare nunc, non auctor arcu condimentum in. In hac habitasse platea dictumst. Etiam porta mattis urna eget sollicitudin. Suspendisse egestas suscipit turpis sit amet dictum. Donec molestie facilisis sagittis. Praesent luctus tincidunt enim, non iaculis est dictum eu. Quisque nunc orci, adipiscing quis fringilla sed, tincidunt nec felis. Quisque id risus magna. Sed ligula purus, aliquet ut feugiat non, consequat vel odio.Note the [img] tags should not include spaces, otherwise they will not work. These spaces have been added so you can see what they would look like before you hit the <Post> button. Others, with a more teachery style can perhaps elaborate. But, I hope this helps to start. Thanks. Skj.
