I am a little unsure of exactly where you are in the process, but here we go.
You need to set up a web host, there are many available and a simple search for "web hosting" will yield plenty of results. Starting out, you won't need a high bandwidth, and space is pretty cheap, the cheapest hosting gig should work, although I recommend against free hosting as it makes it irritating to visit your site. Most web hosts will offer to register a domain name for you, it's been a while, but in my experience, about $20 for two years or so.
When you have your hosting set up, and have been given a user name and password, you just need a ftp program, you can find some for free (WS_FTP LE) or find a good, cheap one (Cute FTP). You use the ftp program per it's instructions to upload your content and there you go.
Anything unclear, or any more information you need?