All you have to do is email in the post. You can save the email address of the site and and then email pictures from your iphone or any other phone with email.
If you want to answer a post will cruising the site on your iphone you click on the response link which is an envelope and attache your picture.
It really is pretty easy. If you start the thread from your iphone email all responses come via email and you can reply just using the email.
Give it a try

bill