With that question, you have a lot of options.

If you want to start it outside on this forum.
1. Find a popular model.
2. Advertise your product.
3. Make a beta test for your users.
4. Be unique to other exchange platforms.
5. Promote the use of different media platforms like Television, radio, and more. But right now we have the social media to make it easier to access with this exchange.

If you want to run with this our forum you can make
1. Announcement board or thread (ANN)
2. Run a signature campaign.
3. Make an event to your platform like bug hunting.