<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>