Pages are rendered using MarkDown. Markdown is quick to write, friendly to read and very forgiving. Alternatively, any HTML written directly will be maintained.
If a page should use a different template to the Default template, then the first line of the file should be :NameOfTemplate
If content needs to be laid out in multiple sections, then these are separated by @NameOfSection at the beginning of a line. By default, all content is used to populate the Body placeholder in the template. Default properties such as Title can be overridden by defining a @Title section. If content should be kept as plain text then place it on the same line as the section name, e.g.:
@Title this is a plain text title @Body This is content to be turned into HTML.
If you define a section for a placeholder that doesn't exist in the template, then it will not be rendered.