Inserting Widget on a webpage
As detailed out in the Customisation & Display rules page, save the configurations to get the code snippets. There will be 3 - one for each type of mode (floating, in-line, pop-up). This is how the page will look like, once the code snippets are available. (notice the right hand section)
Copy the code for your mode & insert it into the HTML of your webpages.
Just to try it out, you can use something like CodePen - Create a New Pen and insert your snippet, to immediately experience the widget in action.
Check out a live demo here - Embedder for Confluence Live Demo