2.Scroll down to where you see </head> tag .
3.Copy below code and paste it just before the </head> tag .
<style type='text/css'> #search { height:34px; width:auto; margin-top:10px; padding:17px 5px 10px 15px; width:311px; background:url(https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg06t-9C9zDZhJI_O4kjygG5zV61hnqzR05HW_xAZL4N1w_IRFiayi5AcEN7R-84EK9xBku35u52n4Vz7IxcLkdAIZ8q08kr-1Uqg4jt0as0Wq1aRLHNPWmarlGPN19Dp9cpOsXCl1-Y-Yy/); } #search form { margin: 0; padding: 0; } #search fieldset { margin: 0; padding: 0; border: none; } #search p { margin: 0; font-size: 85%; } #s { margin-left:0px; float: left; width:231px; padding: 6px 2px 6px 5px; background:#fff url(https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKIh28ellN8dJb_G8i8DGVImRH7GBv3_XVoPOxiVQcrUIyCJycw5wfcDDGHiiicxlB5hdm97Qi8Odq78CTPiJyk1IJPqNimv7op_B0WMvd-Om8tY9DxonYSfvFmYSV4FmEqUoW178DKkWH/s1600/sform.png) no-repeat; border:none; font: normal 100% "Tahoma", Arial, Helvetica, sans-serif; color:#C6C6C6; } #searchsubmit { width:57px; float: left; background:#fff url(https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsjiyCXF9FNyYrpyUnblc17gIFtgt_Brq4W4OfLATVZSaKzpmlM1xt2uTBvZpIpMqVPtlK4Gptq7gM0tudf-4zC2MJg0VAD0de5Jl1LpIvBMGqgXCwQkyH5c-BUcBg9dlz2Y_xZhrxxz9Z/); border:none; font: bold 100% "century gothic", Arial, Helvetica, sans-serif; color: #FFFFFF; height:28px; margin-left:5px; } </style>
Note:Please host above 3 images yourself.
4.Now save your template.
5.Go to Layout-->Page Elements and click on "Add a gadget".
6.Select "html/java script" and add the code given below and click save.
<div id='search'>
<form id="searchform" action="http://YOURBLOG.blogspot.com/search" style="display:inline;" method="get">
<input id="s" name="q" type="text" value=""/>
<input id="searchsubmit" value="" type="submit"/>
</form>
</div>
Note: Remember to replace "YOURBLOG" with your blog name.
You are done.It will look like this: