<nav class="navbar navbar-fixed-top" role="navigation">
    <div class="container">
    <div class="navbar-header">
      <a class="navbar-brand" href="#">Titre</a>
    </div>

      <div class="collapse navbar-collapse">

      <?php
        if ( 1 == 1 )
          {
            ?>    
              <form class="navbar-form navbar-right" role="search">
                <button type="submit" class="btn btn-default">Inscription</button>
                <button type="submit" class="btn btn-default">Connection</button>
              </form>
             <?php
          }
        else
          {
            ?>
              <p class="navbar-text navbar-right">Bienvenue,_
                <a href="#" class="navbar-link">enanrock</a>
              </p>
            <?php
          }

     ?>

      </div>

    </div>
  </nav>