This theme is brought to you without big documentation, guaranties and support (for now). It is only a version of the theme used at https://leah.is, my private blog.
You have to put your posts in a folder called posts under the content folder of your site project.
Static sites are possible with the menu = "main" option in your markdown file header and directly under the content folder.
Images in a post header are possible with image: /assets/images/new_page.jpg in the same header.