Moving navbar below header bootstrap

Question

I am quite new to bootstrap and I was wondering if anyone could give some advice as to how I would be able to place my navbar underneath my header. This is my current code for the two:

Header:

        <div class="row">
            <div class="col-lg-12">
                <div class="intro-message">
                    <h1>HOST</h1>
                    <h3>two is better than one</h3>
                    <hr class="intro-divider">
                    <ul class="list-inline intro-social-buttons">
                        <li>
                            <a href="https://twitter.com/SBootstrap" class="btn btn-default btn-lg"><i class="fa fa-twitter fa-fw"></i> <span class="network-name">Twitter</span></a>
                        </li>
                        <li>
                            <a href="https://github.com/IronSummitMedia/startbootstrap" class="btn btn-default btn-lg"><i class="fa fa-github fa-fw"></i> <span class="network-name">Github</span></a>
                        </li>
                        <li>
                            <a href="#" class="btn btn-default btn-lg"><i class="fa fa-linkedin fa-fw"></i> <span class="network-name">Linkedin</span></a>
                        </li>
                    </ul>
                </div>
            </div>
        </div>

    </div>

Navbar:

<nav class="navbar navbar-default navbar-fixed-top topnav" role="navigation">
        <div class="container topnav">
            <!-- Brand and toggle get grouped for better mobile display -->
            <div class="navbar-header">
                <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1">
                    <span class="sr-only">Toggle navigation</span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                </button>
                <a class="navbar-brand topnav" href="/">Host</a>
            </div>

        <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
            <ul class="nav navbar-nav navbar-right">
                <li>
                    <a href="#">Login</a>
                </li>
                <li>
                    <a href="#">Sign up</a>
                </li>
            </ul>

            <form class="navbar-form navbar-right" role="search">
              <div class="form-group">
                <input type="text" class="form-control" placeholder="Search">
              </div>
              <button type="submit" class="btn btn-default">Submit</button>
            </form>

        </div>
        <!-- /.navbar-collapse -->
    </div>
    <!-- /.container -->
</nav>

Any kind suggestions and tips would be greatly appreciated. I am also fairly new to programming so good explanations go along way! =)

Solution

Just change

navbar-fixed-top

to navbar-top

Edit for the second answer:

Change your to

<nav id="myNav" class="navbar navbar-default" role="navigation">

And you will need to add jquery reference and this little script.

var headerHeight = 200;

$(window).bind('scroll', function () {
if ($(window).scrollTop() > headerHeight) {
    $('#myNav').removeClass('navbar-top');
    $('#myNav').addClass('navbar-fixed-top');
} else {
    $('#myNav').removeClass('navbar-fixed-top');
    $('#myNav').addClass('navbar-top');
}
});  

Basically what this does is checks how much you have scrolled from top and when you pass your header height it fixes the nav to stay on top. You just need to change the headerHeight value to your header height.