Connect with Facebook Twitter g+ LinkedLn

I have a form to login, and I want to boost it with Facebbok, Twitter, G+ and linkedLn. What is the easier way to use script to login in please?

<div class="social" id="social">
           <ul>
             <li><a href="#"> <i class="facebook"> </i> </a></li>
             <li><a href="#"><i class="twitter"> </i> </a></li>
             <li><a href="#"><i class="google"> </i> </a></li>
             <li><a href="#"><i class="linkedin"> </i> </a></li>
             <div class="clear"> </div>
          </ul>
        </div>