Untitled

<?php

   if(isset($_POST['submit_text']) && isset($_POST['find_word']) && isset($_POST['replaced_word'])){
       $sub_text = $_POST['submit_text'];
       $fin_text = $_POST['find_word'];
       $rep_text = $_POST['replace_word'];
       if(!empty($sub_text )&& !empty($fin_text) && !empty($rep_text)){
           echo "Ok.";
       }else{
           echo "Please fill all fields.";
       }
   }
?>
<html>
  <head>
  </head>
  <body>
  <form id="myForm" name="myForm" action="index.php" method="post" >
   <p>
      Submit Text<br/>
      <textarea rows="5" cols="40" type="text" id="submit_text" name="submit_text" ></textarea>
   </p>
   <p>
      Find<br/>
      <input id="find_word" name="find_word" type="text"  />
   </p>
   <p>
      Replace<br/>
      <input id="replace_word" name="replace_word" type="text" />
   </p>
   <input id="submit" name="submit" type="submit" value="Submit" />
  </form>
  </body>
</html>