Clients have included Perry Marshall, Ryan Diess, Perry Belcher (highly regarded digital marketers) and many B2B and B2C e-commerce companies that sell from $1MM-$7MM per year online.
I would start by posting some great content related to your seminar in the Group. There's also very targeted, paid advertising now on Linkedin. Creating a "Sponsored" post Ad (like you see every day in your newsfeed) could get alot of people's attention.
Check out this great podcast: http://baconwrappedbusiness.com/joshturner/