注意事項はこちら。
https://qiita.com/K-Kazutaka/items/1a432bda4f723e6757d6
写経用の記事です。

blog/templates/blog/以下にbase.htmlファイルを作成する

base.html

{% load static %}
<html>
    <head>
        <title>Django Girls blog</title>
        <link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css">
        <link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap-theme.min.css">
        <link href='//fonts.googleapis.com/css?family=Lobster&subset=latin,latin-ext' rel='stylesheet' type='text/css'>
        <link rel="stylesheet" href="{% static 'css/blog.css' %}">
    </head>
    <body>
    <div class="page-header">
        <h1><a href="/">Django Girls Blog</a></h1>
    </div>
    <div class="content container">
        <div class="row">
            <div class="col-md-8">
            {% block content %}
            {% endblock %}
            </div>
        </div>
    </div>
    </body>
</html>

post_list.html

{% extends 'blog/base.html' %}

{% block content %}
    {% for post in posts %}
        <div class="post">
            <div class="date">
                <p>published: {{ post.published_date }}</p>
            </div>
            <h1><a href="">{{ post.title }}</a></h1>
            <p>{{ post.text|linebreaksbr }}</p>
        </div>
    {% endfor %}
{% endblock %}