space for div tag

Question

 check the source code 
css 

 .contentdiv

        { 

            padding-top: 10px;

            float: left;

        }

 <div class="maindiv">

        <div class="arrow" style="width:20px">

            <img id="Prev" src="Images/Left.png" height="20" width="20" />

        </div>

        <div class="contentdiv" id='divloaddynamic' style="width: 350px; height: 300px; ">

        </div>

        <div class="arrow"   style="width:20px">

            <img id="Next" src="Images/Right.png" height="20" width="20" />

        </div>

    </div>

In the above code iam loading dynamic content in div id= divloaddynamic
,  while loading content the 2 images were displaying one after the another (no space for div) after loading content in div( divloaddynamic) next image is showing after dynamic content 
my question is how to show gap(space)  between 2 images (prev, next) while loading