[CodeStache]

For your case, you can wrap the Ad codes in a div and use the CSS like this:

#ad_block {
    float: left;
    width: 320px;
    height: 320px;
    overflow: hidden;
    background: #d6d6d6;
    margin: 0 15px 15px 0;
}

Which will make it looks like this:



You have the adjust the rest of the content/images size though.