Help styling a grid row
I'm trying to style my bootstrap layout with a custom css file. I followed a youtube video on how to add grid rows with columns.
Below is my basic layout that I'm trying to style. I thought I was making some progress until I tried to add an image as a background in my header. It shows up in the header and the footer. Is that because they both have a class that says "col-sm-12" Do I need to change the name on a class? And what about the fact that I have a lot of div that says class=row? The video looked the same as my html except for being a fluid container.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Untitled Document</title>
<!-- Bootstrap -->
<link href="css/bootstrap-4.3.1.css" rel="stylesheet">
</head>
<body>
<!-- body code goes here -->
<div class="container">
<header class="row">
<div class="col-sm-12">Content goes here</div>
</header>
<div class="row">
<nav class="col-sm-3">Content goes here</nav>
<main class="col-sm-9">Content goes here</main>
</div>
<footer class="row">
<div class="col-sm-12">Content goes here</div>
</footer>
</div>
<!-- jQuery (necessary for Bootstrap's JavaScript plugins) -->
<script src="js/jquery-3.3.1.min.js"></script>
<!-- Include all compiled plugins (below), or include individual files as needed -->
<script src="js/popper.min.js"></script>
<script src="js/bootstrap-4.3.1.js"></script>
</body>
</html>
