If you use a basic text editor like Notepad to create your HTML, you just type the tags in by hand. It's not difficult, because there aren't that many of them and most of them are fairly easy to remember, but you don't even have to do that if you don't fancy it. There are lots of programs that will create all the tags for you (see the page on Webpage tools to find out more).
But whatever you use to create your webpage, you need to be able to read the tags to understand what is going on, and make sure it looks the way you intended, and that's what I'm going to teach you. Not every tag there is, just the ones you need to construct a basic webpage, plus (if you're very good) a few easy tricks you can use to make it stand out from the crowd.
If the text isn't there, just some tags, you are probably viewing this site through frames - maybe you came here from Ask Jeeves, or via ultraspace.co.uk, both of which use frames. You can get rid of the frames and come here directly by typing "http://www.jonstorm.com/html/start.htm" into your browser's address box (or highlight the above address, copy it with Edit Copy, and paste it into the address box with Edit Paste, which is much quicker than typing it). Then press Return, and this time View Source will show this page's HTML. Honest!
The reason this is such a great trick is that it will work on any site which doesn't use frames (and most don't), so if you see something you like on a webpage somewhere, you can look at the source code for the page it's on, see how it's done, and maybe copy or adapt it for use on your own pages. There is nothing dishonest about this : you can't take other people's pictures or text without permission because of copyright, but tags aren't copyright, so help yourself. No sense re-inventing the wheel.
Something to watch out for. It's very easy to forget that you have minimised or hidden the HTML source code window, and use View/Source to open another one. And another and another, till you have umpteen slightly different copies of the HTML open at the same time. When this happens to you, and it will, make sure you close them all without saving. Each one is a snapshot of how the HTML was when you last saved in that window, so if you save from a window with an early version of your page in it, but you subsequently made lots of changes in another window, all your later chages will be lost.
So you will sometimes find that a website will look great on one computer (or browser) but not so good in another, because the author has used a special feature that not all browsers/computers support. Or designed it to look good in a full-screen window on a large monitor, and didn't check that it worked for people browsing in a window on a small monitor. An easy way to see what I mean is to try changing the size of the window you are looking at this page in. As you make the window narrower, the text reorganises itself to fit the window, so each paragraph has more lines, but fewer words per line. With just text that doesn't matter much, but it does for a lot of pages.
Fortunately, HTML is pretty forgiving, so you don't need to worry about this too much if you keep it fairly simple. But be aware that some people browse with pictures turned off, or with their browser set to ignore the colours you specified, or with your favourite gimmick disabled, and don't place too much reliance on any one particular trick.