What would be the marketing plan for a new social forum site like Quora/Reddit?

[Random007]

What would be the marketing plan for a new social forum site like Quora/Reddit?

My site will be a social platform where everybody can share and earn knowledge also can sell their services and products.

Will also get free domain and portfolio site.

The system will be a non cms based 5 min website building solution.

It will also boost your local seo visibility.

Almost everything done. I need engagement like public interest on my site.

What should be my marketing plan now?