Stop a PHP webpage from reloading & jumping to top when clicking through a gallery.

General information for the website: Estate Agents website
Description of requirements/features: I am trying to prevent the web page - http://homeestateagents.net/property-details.php?propertyID=283041&photo=1 - from reloading and jumping to the top of the page every time you click through the gallery either on the blue arrows underneath the main image or clicking the thumbnails to the right on the main image.
Extra notes: I tried searching for a resolution and I only managed to find out that I possibly need to add a 'return false' to the onClick. I played around with doing this but I had no luck. I also saw preventDefault() may help. But I am struggling with where to start!

Code below:



<a href="property-details.php?propertyID=&photo=
of
<a href="property-details.php?propertyID=&photo=





Photos



addPhoto(
,
,
,
"");


<a href="property-details.php?propertyID=&photo=<img src="" width="" height="" class="image photo" id="photo" alt="Additional Photo of " onclick="return showPhoto(