Ejemplo layout bootstrap

<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Bootstrap</title>
    <!-- Latest compiled and minified CSS -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">

    <!-- jQuery library -->
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

    <!-- Popper JS -->
    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.0/umd/popper.min.js"></script>

    <!-- Latest compiled JavaScript -->
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js"></script>

    <link rel="stylesheet" href="css/estiloboot.css">
</head>

<body>
    <div class="container-fluid">
        <div class="row">
            <header class="col-12 bg-info"><h1>Cabecera</h1></header>
        </div>
        <div class="row">
           <aside class="col-sm-2 col-md-3 bg-success">
               <ul>
                   <li>111111</li>
                   <li>111111</li>
                   <li>111111</li>
                   <li>111111</li>
               </ul>
           </aside>
           <section class="col-sm-8 col-md-6 bg-info" id="contenido">
               <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Tenetur asperiores esse illum qui. Ut laudantium fuga officia esse at harum pariatur dicta. Reprehenderit excepturi quibusdam fuga debitis eaque nemo adipisci!</p>
           </section>
           <aside class="col-sm-2 col-md-3 bg-danger">
           <img src="img/baldosa.jpg" width="50">
        </aside>
        </div>
        <div class="row">
            <article class="col-md-3"><img src="img/baldosa.jpg" width="100"></article>
            <article class="col-md-3"><img src="img/baldosa.jpg" width="100"></article>
            <article class="col-md-3"><img src="img/baldosa.jpg" width="100"></article>
            <article class="col-md-3"><img src="img/baldosa.jpg" width="100"></article>
            <article class="col-md-3"><img src="img/baldosa.jpg" width="100"></article>
            <article class="col-md-3"><img src="img/baldosa.jpg" width="100"></article>
            <article class="col-md-3"><img src="img/baldosa.jpg" width="100"></article>
            <article class="col-md-3"><img src="img/baldosa.jpg" width="100"></article>
            <article class="col-md-3"><img src="img/baldosa.jpg" width="100"></article>
            <article class="col-md-3"><img src="img/baldosa.jpg" width="100"></article>
            <article class="col-md-3"><img src="img/baldosa.jpg" width="100"></article>
            <article class="col-md-3"><img src="img/baldosa.jpg" width="100"></article>
        </div>
        <div class="row">
            <footer class="col-12 bg-warning"><p>Esto es el pie</p></footer>
        </div>
    </div>

</body>

</html>

article{
    background-color: paleturquoise;
    border:1px solid black;
}
@media (max-width:576px){
  #contenido{
      order:-1;
  }
}