There isn't one. There are several. And which you use depends on what you want to study.
Do you want to offer dedicated hosting? Then you'll want to find a place to buy and house your dedicated server, or a company that sells dedicated servers which you can then resell.
Don't know how to manage a server? You'll need a web site to learn that. (But of course, you'll need to know which OS you're going to be managing, and learn all of its quirks and secrets, too.)
Want to offer web design services? Then you'll want to know HTML/CSS/PHP, as well as how to customize and develop the more popular software packages.
The questions just go on, and on, and on. (And I haven't even touched on the business issues yet: billing, taxation, registration, customer rights, liabilities, employee issues, and more.)
If you don't know anything, your best bet is to hang around forums that cover the topics you want to learn, read the threads to learn, participate (because asking questions expands your knowledge, and answering them can help you retain the knowledge), lather, rinse, repeat. You've already found one site - this place. There are plenty of others out there, each with their own specialties and areas of focus (as well as community feel and general environment.)
The process never, ever ends. Some days you may feel like screaming...but you'll never, ever be bored.
Welcome in. Newbies buy the beer