At the top of the home page, in the blue side bar you'll see the link "Plant Database".
To share your pictures eg. the lovely iris start at the home page again, click on "Irises" in the list of forums then pick a thread to join. When I join a new thread I usually read at least the last few pages of posts so I can see what the chat has been about, then at the bottom, just like you do here, write a post and upload your images. If you have the names of your cultivars, it's nice to put those in but nobody minds seeing beautiful flowers even if you don't know their names.