<!DOCTYPE html>
<html>
  <head>
    <title>My Open Tabs</title>
    <link rel="stylesheet" href="bootstrap/css/bootstrap.min.css">

    <style>
      body {
        width: 500px;
      }

      #favicon {
        width: 16px;
        margin-right: 10px;
      }

      .label {
        margin-left: 10px;
      }
    </style>

    <script src="jquery.min.js"></script>
    <script src="popup.js"></script>
  </head>
  <body>
    <ul id="tabs" class="list-group"></ul>

    <label>Total de <span id="tabs_count"></span> abertas.</label>

    <center>My Open Tabs &copy; 2015</center>
  </body>
</html>

<!DOCTYPE html>
<html>
  <head>
    <title>My Open Tabs</title>
    <link rel="stylesheet" href="bootstrap/css/bootstrap.min.css">

    <style>
      body {
        width: 500px;
      }

      #favicon {
        width: 16px;
        margin-right: 10px;
      }

      .label {
        margin-left: 10px;
      }
    </style>

    <script src="jquery.min.js"></script>
    <script src="popup.js"></script>
  </head>
  <body>
    <ul id="tabs" class="list-group"></ul>

    <label>Total de <span id="tabs_count"></span> abas abertas.</label>

    <center>My Open Tabs &copy; 2015</center>
  </body>
</html>

Add text on the count label
Add  text on the count label
