Your material will be created in the window "Content". Here you have various tools for text formatting and for adding images. 

It is suggested that you paste your letter as a text and edit it using the functions of the site editor.

Choose the title that summarises the letter well for the potential reader.

Below the editor's window there are some buttons for additional functions: add an attachment, link the article, image, pagebreak (useful if your material is rather large and it has index), and button "more" (for introduction, i.e., for a blockquote when clicking on "more" opens whole material).

If you would like to add comments to the editors, include them in the end after your letter clearly marking that it is the text for the editors.