Q: How to build a dream house when you are not a builder?

A: Talk to an architect ... or a foreman ... or someone who has built a house like the one you envision.

If you're not sure what kind of scope your web project requires, that's fine. At least, begin by talking to a software developer or a web designer. They'll have a better sense for what's required.

Are you thinking about a website? Or a web-application? There are plenty of web development companies (from low cost to great team and reputation) out there which you can share your requirement to them and get a quote. If you are just building a prototype to test your idea, you can even get freelance developers and designers to do it. Go to some known hubs where developers and designers are known to gather in your area and start talking to people.