FTP access and plugins are only for VIP bloggers http://vip.wordpress.com/our-services/ or for those with WordPress.ORG installs.
There is no FTP access to our free hosted WordPress.com blogs and we cannot install plugins. If you must have plugins then you have to hire a web host and set up your own WordPress.org install. Read the comparison here please > http://support.wordpress.com/com-vs-org/
Also note that there are many artists and photographers I know here here who would like to be able to insert the script from Pinterest that prevents the pinning of their original drawings, paintings and images but as this is a multiuser blogging platform they cannot do this.
As you are new to WordPress.com the step by step tutorial is the way to go. It's linked to on the bottom of your Admin page at http://learn.wordpress.com