yeah man, no worries...
in the theme you use, find the area that in responsible for presentation of your ad's. You will be modifying that file with a little html...
before any of the ad's start, you are going to want to open a new div. If you used the example I provided it will be advert_container, and will look like this:
<div class="advert_container">
either at the end of that particular ad or at the end of all your ad's in that particular area (left sidebar for instance) you will want to close that div:
</div>
then you will want to open your style.css and add the css modification/addition I provided above.
There may be an instance where you are wanting to contain a skyscraper banner ad (narrow but tall) or a traditional banner (short but wide) or a badge (square or close to) which you may want to write additional css declarations for... for instance:
.advert_container_skyscraper {
height:800px; /*or defined max height*/
width: 120px; /*or defined max width*/
}
.advert_container_skyscraper img {
height: 90%;
width: 90%;
margin:auto;
}
.advert_container_skyscraper script {
height:90%;
width: 90%;
margin:auto;
}
and:
.advert_container_traditional_banner {
height:200px; /*or defined max height*/
width: 800px; /*or defined max width*/
}
.advert_container_traditional_banner img {
height: 90%;
width: 90%;
margin:auto;
}
.advert_container_traditional_banner script {
height:90%;
width: 90%;
margin:auto;
}
and:
.advert_container_badge {
height:200px; /*or defined max height*/
width: 200px; /*or defined max width*/
}
.advert_container_badge img {
height: 90%;
width: 90%;
margin:auto;
}
.advert_container_badge script {
height:90%;
width: 90%;
margin:auto;
}
of course, if you are needing to contain a skyscraper, you would want to insert the html division declaration specific to that ad placement... i.e:
<div class="advert_container_skyscraper"> all your ad code</div>
Now, very specific to your issue, I would create a div class in your css and call it whatever, but for speaking purpose let's say it is called left_bar_ad...
it would be:
.left_bar_ad {
height:200px;
width: 200px;
margin:auto;
}
.left_bar_ad img {
height:90%;
width:90%;
margin:auto;
}
and then find where you inserted the ad in your theme, and ad to that file immediately preceding the ad:
<div class="left_bar_ad">the SINGLE ad</div>
this should center as well as scale the ad's presentation on your page.