[Answered ]-Submit without refresh – Django

First learn Javascript and Jquery and Ajax to understand more clearly.
http://www.tutorialspoint.com/jquery/
http://www.w3schools.com/jquery/

template ‘event.html’:

{% if user in event.users.all %}
    <form action="/event/{{ event.id }}/" method="GET" id="event">
    {% csrf_token %}
    <input type="hidden" value="{{ event.id }}" name="remove">
    <input type="submit" class="btn btn-warning btn-block" value="{% trans "Remove from My Events"%}">
    </form>
{% else %}
    <form action="/event/{{ event.id }}/" method="GET">
    {% csrf_token %}
    <input type="hidden" value="{{ event.id }}" name="add">
    <input type="submit" class="btn btn-primary btn-block" value="{% trans "Add to My Events"%}">
    </form>
{% endif %}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.0.0-beta1/jquery.min.js"></script>
<script>
$('#event').submit(function(e){
    e.preventDefault();
    url = $(this).attr('action') # to get url
    data = $(this).serialize(); # for sending form data 
    $.post(url, data, function(response){
          # do whatever you want with response(data)
    })
})
</script>