How do you change the photos on the side of the pages under Our Photos?

Most likely the Our Photos section on your website is running a feed from your Photos module to keep the content automatically updated.

Most feeds are set to pull the most recent Photos while some sites chose to display Photos from a particular Album to highlight a location or event.

To see where your feeds are originating, access the Theme Editor and pull up the sidebar.html template. Look for code similar to this:

<div>
  <h3 class="headline">{% trans 'Our Photos' %}</h3>
  {% cache 36000 photos_cache1 %}
  {% list_photos as photos_list limit=12 random=True %}
  <ul class="list-unstyled">
    {% for photo in photos_list %}
    <li class="col-sm-2 photo-thumb"><a href="{{ photo.get_absolute_url }}"><img alt="{{ photo.title }}" src="{% photo_image_url photo size=62x56 crop=True %}" /></a></li>
    {% endfor %}
  </ul>
  {% endcache %}
  <p><a href="/photos/" >{% trans 'View More Photos' %} &raquo;</a></p>
</div><!--/#photos-->

In this example, the Photos are pulling 12 Photos at random from the latest Photo Album (default) and displaying a cropped image that links back to the full Photo file.