Who would you need to build a website?

I want to create a website that would require a privacy policy, term and conditions of the website, disclaimer and terms of a contract for billing purposes, the billing would be via credit card or a 30 day billing invoice. The website would have to be built from scratch. Would require maybe 300,000 users. And I would need to market it afterwards. I would also have to start a LLC for the business. Who do you think I would need to accomplish this?