how to add comments box in html code example

Example 1: how to create comments in html5

Insert a single-line, or multi-line comment. 
Comments are designated by the tags <! -- and -->

Use the comment function to hide scripts on unsupported browsers
. If you are programming in JavaScript or VBScript, 
you can use the comment function to hide the script on browsers 
that don't support it. Insert the comment at the start of the 
script, and end it with //--> to ensure that the script works 
on browsers that do support it.

Example 2: html how to add comment

<!-- This is the first comment, it won't be shown on a page -->

<h1>And this is a header. It will be fully visible.</h1>

<!--
Multiline comment.
You can place a lot of information there.
Maybe even a whole book.
-->