Search Form Dynamic

Step 01: use the code where needed and to style it properly follow the step 02
<?php get_search_form(); ?> <!--this function will look for searchform.php file-->

Step 02: create a new file as 'searchform.php' and dynamic the html code there
Your HTML code was this:
<form action="" id="search-form" method="get">
     <input type="text" value="search" onblur="if(this.value=='')this.value='search'" onfocus="if(this.value=='search')this.value=''" />
    <input type="hidden" value="submit" />
 </form>

Now your dynamic code in searchform.php will be like this:
 <form action="<?php home_url(); ?>" id="search-form" method="get">
     <input type="text" value="search" name="s" id="s" onblur="if(this.value=='')this.value='search'" onfocus="if(this.value=='search')this.value=''" />
     <input type="hidden" value="submit" />
 </form>