Hola, aqui adjunto mi codigo HTML de la pagina de aves que nos mandaron a hacer. Tengo unas duda, es respecto a elemento <nav>; para que la página me quedara como mostraba la foto que nos proporcionaron tuve que poner al elemento <nav> dentro del elemento <header> y no estoy de si eso es correcto.
Codigo HTML 
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Birdwatching</title>
<link href="https://fonts.googleapis.com/css?family=Roboto+Condensed:300%7CCinzel+Decorative:700" rel="stylesheet">
<link href="style2.css" rel="stylesheet">
<!--[if lt IE 9]>
<script src="https://cdnjs.cloudflare.com/ajax/libs/html5shiv/3.7.3/html5shiv.js"></script>
<![endif]-->
</head>
<body>
<header>
<h1>Birdwatching</h1>
<img src="dove.png" alt="a simple dove logo">
<nav>
<ul>
<li><span>Home</span></li>
<li><a href="#">Get started</a></li>
<li><a href="#">Photos</a></li>
<li><a href="#">Gear</a></li>
<li><a href="#">Forum</a></li>
</ul>
</nav>
</header>
<main>
<article>
<h2>Welcome</h2>
<p>Welcome to our fake birdwatching site. If this were a real site, it would be the ideal place to come to learn more about birdwatching, whether you are a beginner looking to learn how to get into birding, or an expert wanting to share ideas, tips, and photos with other like-minded people.</p>
<p>So don't waste time! Get what you need, then turn off that computer and get out into the great outdoors!</p>
</article>
<aside>
<h2>Favourite photos</h2>
<a href="favorite-1.jpg"><img src="favorite-1_th.jpg" alt="Small black bird, black claws, long black slender beak, links to larger version of the image"></a>
<a href="favorite-2.jpg"><img src="favorite-2_th.jpg" alt="Top half of a pretty bird with bright blue plumage on neck, light colored beak, blue headdress, links to larger version of the image"></a>
<a href="favorite-3.jpg"><img src="favorite-3_th.jpg" alt="Top half of a large bird with white plumage, very long curved narrow light colored break, links to larger version of the image"></a>
<a href="favorite-4.jpg"><img src="favorite-4_th.jpg" alt="Large bird, mostly white plumage with black plumage on back and rear, long straight white beak, links to larger version of the image"></a>
</aside>
</main>
<footer>
<p>This fake website example is CC0 — any part of this code may be reused in any way you wish. Original example written by Chris Mills, 2016.</p>
<p><a href="http://game-icons.net/lorc/originals/dove.html">Dove icon</a> by Lorc.</p>
</footer>
</body>
</html>
