How to get freelancers to work on your website?

Releasing a website soon to connect ordinary people, students, business men with teachers and professionals, how do I recruit the teachers and professionals?

1. First, it has to serve a purpose great enough to peak people's interest. If your site offers that, then incentivize the users.
2. Give free access. If the site fulfills a need great enough, the free access will expose it to your market and the fulfilled need will cause them to share with peers.

The channel that will work best for you depends on the niche your site is in.

Since you state you would be recruiting these teachers, I'm presuming it's a paid position.

Here are some strategies:

• Post ads on craigslist
• Post a "remote ok" job on AngelList and other relevant sites where you audience is. i.e. AngelList would only work if you're recruiting software engineers, designers, or marketers.
• Figure out which meet-ups your audience attends, and try to recruit them in-person.
• Graduate students are usually willing to teach their newly learnt skills. You could pitch to them as an internship.