title: Error submit form data from frontend to store in wordpress database using my plugin
body: <p>I wrote a plugin code. I want to show a custom form using my shortcode made by my plugin at every page I like. The Plugin and the form show correctly but after submitting and processing data to store on the database page not found error occurs. what is the best way to submit data from the frontend to the backend?</p>
  
  <pre><code>// this is my shortcode function code:
  &lt;?php
  if(isset($_POST['submit_btn']))
  {
      // inserting data to database process that currently ends with
      // Page not found error.
  }
  ?&gt;
  &lt;form method="post"&gt;
      &lt;input type="text" name="name"&gt;
      &lt;input type="submit" name="submit_btn" value="Store"&gt;
  &lt;/form&gt;
  </code></pre>