Look at the photo. What has just happened here? What is about to happen? Who has been in this place? Who will come here and and what will they do? What kinds of interactions can you imagine? Write one leaf beginning with what occurs to you upon looking, but do not allow yourself to be limited by what you see.
Write One Leaf is about writing every day. Write one leaf; one word, two pages, three notecards, four napkins, five blog posts, &c. But begin. Use your hands. The best way to get started is to get started. Write. Right now.