How to create a website?

[T]

How do I go about creating a website? I have read a lot about it online but I'm still not exactly sure what to do. I understand that I have to buy a domain name online, but who am I buying this off? There are hundreds of sites and if I type in a domain name that's available, they all say I can buy it off them for a certain price. Surely they can't all own every free domain name, so do they then go and buy it off the main supplier and sell it on to me?

Next, if I pay to use that domain name for a year and then it expires, aren't the website free to charge whatever they want for me to renew it each year? What if my website becomes huge, like Facebook. Doesn't it mean that they could charge me millions and I'd have to either pay up or change domains?

Once I've bought the domain, where do I actually go to create the website itself. I have a good idea of how I want the page laid out but where will it actually be stored. For example, where are sites like MoneySavingExpert.com stored? Do I create the website and then link it to the domain name?

Thanks for your help.