You can find Mosspaper's Widget here: https://app.mosspaper.com/d/#/widget. There are 2 sizes available for you to embed into your web site.
2) Select the page you would like to display the widget.
3) Select on "Add an element".
4) Scroll down to "html".
5) Drag and drop the html into a designated area.
6) Add the iframe html code into the box.
Check out the widget here: http://mosspaperwidget.dudaone.com/