where in analytics can i see the ad box that's mostly clicked by users?

as the tittle goes,
where in analytics can i see the ad box that's mostly clicked by users?

 

what I have understood from your question is that you want to know the click patterns on your site, in analytics you can use the "click overlay" feature which shows percentage wise division of areas on site where you are getting the clicks.

 

You can also place a query string on specific ad boxes (if internal) and capture it in a custom variable. Otherwise Google should automatically track exit links.