Correct image path

I am testing out some ad implementations in my theme template on my local Xampp before going live. But I can’t get the correct image path, image doesn’t get visible.
This is how I try to show it in home.php:

<div id="topbanner" class="column span-14">   <!-- start top banner -->
             <div class="pagetitle column span-7">
                  // index
             </div>
             <div class="column span-7 last">
                  <a href="#"><img src="http://localhost/testside/images/bg/ad_468-70.png" alt="here it is"></a>
             </div>
        </div>   <!-- end top banner -->

When adressing just images/bg… it’s the same. Any advice? Do I have to make a included php into this div?