Check out example codes for "online html editor". It will help you in understanding the concepts better.

Code Example 1

#I recommmend https://codepen.io/pen/

Code Example 2

<!-- Answer to: "online html editor" -->

<!--
  A common good "online editor" would be:
  https://jsfiddle.net/

  However, for an online editor focusing specifically on html
  this one is pretty good:
  https://html-online.com/editor/
-->

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