There is no FTP access to free hosted WordPress.COM blogs like the one linked to your username and we cannot install individual plugins or third party themes into them for security reasons. Those found on the internet are for WordPress.ORG installs which run on different software.
More to the point is this. There is only one advertising program called WordAds at WordPress.com and it’s for blogs on their own domains. This is the homepage for the WordAds program: http://www.wordads.co/ There you will find the application page as well as FAQs.
Aside from a blog being accepted into WordAds, no blogger initiated advertising, retailing or reselling the work or products created or services provided by anyone other than yourself is allowed on free hosted wordpress.com blogs. E-commerce transactions via shopping carts and the like cannot be conducted on free blogs from and being free hosted by wordpress.com
If you do require an ecommerce site, advertising and/or affiliate links you can hire a web host and get a free software install from http://wordpress.org Refer to > http://support.wordpress.com/com-vs-org