You need to add the relevant javascript and CSS linked on the page:
(either the minified or the pretty, they are the same code, but different formatting)
Then use the <<character>> macro to set up the character in the StoryInit special passage:
<<character 'name' 'The Name Displayed on the page' 'the URL of the image'>>
(if you don’t include the The Name Displayed on the page, the macro will display name instead)
Then in the passage you want to use:
<<name>>Whatever text you want in the box<</name>>
(the name is the same as the first defined element in <<character>>)
Or you can just use <<say>> without having to setup the box in StoryInit:
<<say 'name' 'URL of the image>>Whatever text you want in the box<</say>>