If you are using PHP this will help you :
<html><body><center><form method='POST' id='top'>
<input type='text' name='search_word'>
<input type='submit' name='submit' value='search'>
</form>
<?php if(isset($_POST['submit'])){ ?>
<input type='button' value='Clear' onclick="window.location.href=''">
<?php $search_word=$_POST['search_word'];
echo"<script>document.getElementById('top').style.display='none';</script><div id='search_div'>
<iframe src='https://www.google.com/search?igu=1&ei=&q=$search_word' frameborder='0' width='90%' height='90%' allowfullscreen></iframe></div> "; } ?>
</body></html>