Help for Starting up a Business Website?

I understand the basics of computers, but I'm not a coding expert, all I have is trivial experience with HTML, but I do have interested contacts that have extended coding experience. I'm at a loss at where to start; there are lots of providers easily available, but I need something a little less basic: the conceived site would be very large and user-based, requiring extended space for forums and copious amounts of pages. In addition, speed and robustness can't be sacrificed for size, because clutter and a confusing interface would drive users away, the target demographic in particular. Are there sites that could supply such an intricate website design (and content) to an entry-level client like me? I'd be happy to re-evaluate the question, and I appreciate any help at all, even if it's bad news. Thank you.