How to create Search Engine in PHP for website

HTML code for Search-Box

<div class="search-box" >

<form action="search.php" method="get">

     <input id="text-style" type="text" size="25"  name="search" placeholder="search this site..." required>

     <input id="button" type="submit" name="submit" value="Search">

</form>

</div>

CSS For Search-box

 #text-style

{

  height:16px; 

  border-radius:4px;

  margin-top: 2px;

  padding:2px;

  border:0px solid #dbdbdb;

 background:#dedede;

}

#button

{

  border: 2px solid #207cca;

  background:#207cca;

  border-radius: 2px;

  margin-top: 3px;

  width: 60px;

  height:28px;

  cursor: pointer;

  font-weight: bold;

  font-size: 14px;

  color:#fafafa;

}

#button:hover  

{

background-color:#fafafa;

color:#207cca;

}

PHP code for search engine

<?PHP

$servername = "localhost";

$username = "root";

$password = "";

$db="my database";

$con = new mysqli($servername, $username, $password,$db);

if ($con->connect_error) {

    die("Connection failed: " . $conn->connect_error);

}

if(isset($_GET ['submit'] )){

$search_id = $_GET['search'];

$query="SELECT * FROM posts WHERE post_title  like '%$search_id%'";

$result=mysqli_query($con,$query);

while ($row=mysqli_fetch_array ($result)){

$post_id=$row ['post_id'];

$post_title=$row ['post_title'];

$post_image=$row ['post_image'];

$post_content=substr($row ['post_content'],0,1000);

}

?>

<h2> 

     <a href="pages.php ?id = <?php echo $post_id;?>">

           <?php echo $post_title;?> 

      </a> 

</h2>

<center>

<img src="images/<?php echo $post_image;?>" width= "100" height= "100"/>

</center>

<p align=justify>

<?php echo $post_content; ?> 

</p>

<?php } ?>