You can put anything into the full screen text template using the WYSIWYG editor or by clicking on the HTML option in the bottom left corner of the editor. If you are copying and pasting, be sure to remove any <DIV> tags that would affect the placement on the screen etc. so that everything stays relevant to the template.
There's a tool in the editor to automatically remove any unwanted tags, or you can do it manually by going into the html editing mode.