Somewhere, your data is stored on someone's drive. It could be at your own ISP (Internet Service Provider), or on your own system if you have a permanent connection to the web, or you can pay another service provider to host the pages for you, or you can use one of the many free web hosts. There's a myriad of choices.
This is probably the simplest way to do this, and usually the only drawbacks are: If you decide to change ISPs at some point in time, you have to redirect people to the new site. And if your site gets swamped with visitors your ISP may get annoyed with you, and terminate your account. It always pays to check the terms of service you have with an ISP, and ask them directly if you're unsure about something.
This has it's advantages of always been directly under your control, but the disadvantages that if your system goes off-line nobody can access your pages; if your system is insecure, strangers can wreak havoc on it; or your system get bogged down simply by the number of people accessing the site, or them downloading masses of files.
This is mostly the same as having them hosted on your own ISP, but can have some advantages. Another ISP may have a better deal regarding hosting pages than your current one, but you want to keep your current one for the services you use now. And if the site gets swamped due to heavy use, for instance, your normal internet activities will not be affected.
They have the following disadvantages: They're usually more restrictive about what you can serve (quantity, type of content—commercial vs personal, etc.). They often insist on you submitting to surveys. They usually insist on including their own advertising on the site (which can often can be appallingly garish or inappropriate). Their servers are often swamped, and access can be slow or impossible quite often.
There are basically three ways your web site will be named:
When you join an ISP, you often get your own web page space on their system, it will usually have an address that begins with the ISPs address, and has your own user name appended to it.
If you wanted to have an address like www.example.com, then you would have to pay to have the name entered in the Domain Name Servers (DNS) world-wide (though you're virtually paying for the addition to a DNS server and they spread the address world-wide between themselves, i.e. if you're listed, it's a global listing, not just a local one).
This can cost upwards from $20 a year. It's the internet equivelent of the telephone directory—people will be able to type in your chosen name into their browser, and the DNS service will tell their browser whichever server is actually hosting the site. Should you need to relocate your site, you can change the address the DNS service directs people to, and everyone will be directed to the new location none the wiser (the changeover isn't instant, it has to propagate throughout the whole system—which usually should only take a few hours, but depends on how often each DNS updates its own listing).
Remember though, this will cost you on top of whatever you already pay for your access to the internet.
Once again, there are basically about three ways. They can be told about it by you directly, they can find it through traditional advertising, or by an internet search engine (perhaps by name, or by making a query on a topic your web site deals with). A search engine is probably going to the way most people will find your website.
By and large, all search engines only know about web sites that have been submitted to them (either by the web site owner, or someone else decided to add the information after finding your site), or the engine finds the site listed on another site. So you'll need to submit your site to one or more search engines or ensure it's listed on a service that a search engine will notice, if you want people to be able to find it that way. If you submit it yourself, you may have more control over the additional information that it can classified under, as well as being able to remove your site from their index.
If you're submitting your site to a search engine, think about whether your site really is a world-wide point of interest, or whether you'd be better of submitting it to a search engine that is aimed towards other users in your own country. Also look for search engines that don't make you pay for this service, and ones that will offer your information to several other search engines as well. And ones that don't deluge you with junk mail because they now have your address on their database (check for their anti-spam and privacy policies). Google is probably the most well known and respected search engine.