In short, you can't. Without a lot of help.

The jerks will say "Ideas are like assholes: everybody has at least one." But the basic premise is right. The only difference between you and Mark Zuckerberg is that Mark Zuckerberg did what almost nobody else does: Followed through. If you had a unique idea (hint: you don't) and got a UX designer to mock it up, and pitched it to a venture capitalist, and they gave you money to pay for it to be built... ok, then you might have something someone might sell online for $5-15, if people don't just pirate it.

Oh. And Confluence already does what you want. In fact, what you want is a Content Management System, aka CMS, which can be as simple as a wiki of which there are oodles of them to choose from, or as complex as Savo.

I have personally designed a content management system (for Kaiser Permanente's printing services division, using a database called Helix), a Competitive Intelligence Library (for F5, using Confluence), and produced highly detailed and unique documentation library (in LaTeX for Applied Materials, the people who make the machines that make semiconductors), and am now working on content management for a new company.

In short, make a list of the three features you need. Then ask around. Download a lot of stuff and try it out. Find the two apps that meet those needs the best you can, and run one of them.

In a year the entire project will change anyway, and whatever you decide on won't meet the new (entirely unexpected) requirements. Nothing beats a well-organized directory on a file server, expect for meticulously managed wikis. That's the long and short of it.