how to manually add submission input to a form html code example

Example: html form

<form action="/action.php">
  <label for="fname">First name:</label><br>
  <input type="text" id="fname" value="Mike"><br><br>
  <label for="lname">Last name:</label><br>
  <input type="text" id="lname" value="Walker"><br><br>
  <input type="submit" value="Submit">
</form>

Html By Duco Defiant Dogfish on Feb 11 2020
<form action="/action_page.php">
  First name:<br>
  <input type="text" name="firstname" value="Mickey"><br>
  
  Last name:<br>
  <input type="text" name="lastname" value="Mouse"><br><br>
  
  <input type="submit" value="Submit">
</form>