Ads in sidebar / CSS padding

I’ve added a plugin, AdRotator, that is working great, except with the existing CSS for the padding as applied to widgets in the sidebars.

For example: http://lariatnews.com/sports/saddleback-womens-basketball-wins-against-cypress/

I’ve tried several times to figure out how to add custom CSS specific to this particular widget to no avail. I’m an old-school HTML coder but for the life of me cannot figure this one out.

Your assistance with this would be greatly appreciated and thank you in advance.