title: How to add category to my polls app?
body: <p>My models.py is</p>
  
  <pre><code>class Question(models.Model):
      question_text = models.CharField(max_length= 100)
      pub_date = models.DateTimeField('Date Is Published')
      image = models.ImageField(upload_to="Question_Image", blank=True)
  
      def __str__(self):
          return self.question_text
  </code></pre>
  
  <p>And, I have to add a class "category" so that each of my question could select one of four categories: world, technology, screen and sports.. For example, my one category html i have is screen.html and i need to display only questions based on category 'screen'. Here's my screen.html.</p>
  
  <pre><code>{% extends 'polls/base.html' %}
  {% block main_content %}
  {% if latest_questions %}
  &lt;body&gt;
      &lt;ul style="list-style: none;"&gt;
          {% for question in latest_questions %}
          &lt;li style="float:center"&gt;
              &lt;div id="tabs"&gt;&lt;a id="tabsword" href={% url 'polls:detail' question.id %}&gt;
                  &lt;img id="tabsimage" align="middle" src='{{question.image.url}}'/&gt;
                  &lt;p style=" font-size: 25px; font-family: Verdana; color: whitesmoke; text-align: center"&gt;&lt;b&gt;{{question.question_text}}&lt;/b&gt;&lt;/p&gt;
              &lt;/a&gt;
              &lt;/div&gt;
          &lt;/li&gt;
          {% endfor %}
      &lt;/ul&gt;
  {% else %}
      &lt;p&gt; You have no questions. Please add some.&lt;/p&gt;
  {% endif %}
  {% endblock %}
  </code></pre>
  
  <p>Help me modify the codes in a way so that i could add class category, assign each question out of four category and display only questions based on category "screen" on the above html.</p>