Hi Clare, when you're making a post, just below the text box where you type is a tab that says Attachments. Give that a click and then under it you can browse to find your picture. At least that's how I do it on the computer, maybe it's different for an iPad. I moved your post to the "Tinkering with this site" forum since that's kind of the Tech Help section of Permies.
"Hundreds of years from now it will not matter what my bank account was, the sort of house I lived in or the type of car I drove... But the world may be different because I did something so bafflingly crazy that it becomes a tourist destination"