php - how to get avatar on front end wordpress

Hello users of stack over flow, I have a little Question,

I am trying to get avatar in upper end of my website, if user is logged in I want to show

avatar and name and link to profile,

if user is not logged in I want to show login and register buttons

I know little bit of php only , I will have to use if else statement but how to call wordpress logged in user function ,

thanks

(if you provide me with a sample code that will help a lot)

I tried something like this

 <ul >
<?php
if ( is_user_logged_in() ) {
 echo 'Welcome, registered user!';

 <li id="menuLogin" >
    <a title="Register" href="./register?to=">

      Register

    </a>
    <a id="navLogin" data-toggle="dropdown" href="#">

      Login

    </a>
    <div >
      <form id="loginform" method="post" action="./login?to=">
        <input id="user_login" type="text" placeholder="Email or Username" name="log"></input>
        <input id="user_pass" type="password" placeholder="Password" name="pwd"></input>
        <label >
          <input id="rememberme" type="checkbox" value="forever" name="rememberme"></input>

           Remember            

        </label>
  <input id="wp-submit" type="submit" value="Log In" name="wp-submit"></input>
  <input type="hidden" value="http://www.entrytestclass.com/main21/wp-admin/" name="redirect_to"></input>
  <input type="hidden" value="" name="instance"></input>
  <input type="hidden" value="login" name="action"></input>

      </form>

      <div >
        <div id="fb-root" >
          <div ></div>
          <div ></div>
        </div>
        <script>


              window.fbAsyncInit = function() {
              …

        </script>
        <div scope="email,user_about_me,user_location,user_website" size="medium" login_text=" " fb-xfbml-state="rendered" fb-iframe-plugin-query="app_id=332446126861609&locale=en_US&login_text=%0A%20%20%20%…about_me%2Cuser_location%2Cuser_website&sdk=joey&size=medium">
          <span >
            <iframe height="1000px" frameborder="0" width="1000px" scrolling="no" name="f27f166a4e97fde" allowtransparency="true" title="fb:login_button Facebook Social Plugin" src="http://www.facebook.com/plugins/login_button.php?app_id=3324…about_me%2Cuser_location%2Cuser_website&sdk=joey&size=medium"></iframe>
          </span>
        </div>
      </div>
    </div>
  </li>

  }
  ?>

</ul>
Copy code

But I got erros , Please can someone tell me what I am doing wrong