Run social media advertising campaign for a question and answer site

Need an experienced person who is able to manage a social media advertising campaign across different platforms (fb, google, twitter, quora etc) to:
– generate traffic to the site
– to encourage writers/researchers to join and contribute to q&a site
– to get the brand out there

Ideally should have strong demonstrable experience in this area.

Will start with a trial project and if it goes well, can convert to long term.