Text will be the most important means of communication on your site. A site like this for sure. People are visual creatures. More profanely: they rather watch TV instead of reading a book. This means most people are not accustomed to reading. Still text is the most important way of conveying information on a web page.
Video cannot be displayed at the current state of technology. No more than two or three tiny images can per second be squeezed over a modem line. Speech is possible, albeit very limited. You will at least need a good connection, a sound card and appropriate software. Not everyone has these, and even then sound will be very bad. You will just have to make do with text. Supported with some images, to please the eyes.
A point of attention. Not accustomed to reading, people hardly write, if at all. No one writes a letter these days. It is much easier to pick up the phone and say what you have to say. Much faster and more personal. But like I said, you will just have to write for your pages. Some tips seem in order.
Do a brain storm. Write down anything you can think of that enters your mind, concerning the subject you want to write about. Preferably short hand sentences. The order does not matter, or writing style, or grammar. Often you will be amazed of what you can come up with. If you cannot think of anything else, try to group what you have written down. Put things that belong together on a separate sheet of paper. Look if you can put some order in them. Sometimes it may help putting all your thoughts each on a separate card. You can shuffle around with them just as long as you please.
If you did everything right you can write your story like hanging clothes on a hall stand. With some luck you can write a paragraph on each point. This way of working enables you to write fast and structured. A lot faster than just starting to write. Your writing will make a lot more sense. You won't loose yourself in less important matters, that really should not be in the story.
Write short and concise. People are not accustomed to reading. Long text will bore them quickly. If you managed to read this entire site so far, you are an above average reader anyway. Try to captivate, get people curious for the next sentence, the next paragraph, the next page. The reader should feel he misses something if he does not keep on reading.
Inexperienced writers often make sentences too long. The average reader won't understand any sentence longer than thirteen words at once. Not without reading it again. Cut long sentences into smaller pieces. Don't make them to short however, it will have an irritating staccato effect.
Build your text with paragraphs. A central sentence, the rest clarifying it. Properly written text can be read very fast by finding this central sentence in each paragraph. Often the first, second or last sentence in a paragraph. Don't make them too long, about five to ten lines should be enough.
Make a certain build-up in your story. A discourse leading to a conclusion. Or even better, statements supporting what you mention at the beginning of your story. A common trap is to mention important things too often. This can be very annoying, thus rendering your writing useless.
You could show your writing to someone else. Ask him to tell what he just read. You can easily ascertain if he understands what you are saying. He may conclude something different than you meant to say, or he simply did not understand it at all. Keep changing the text until it is clear to him after reading once.
You could also put the text away for a few days before reading it again. You can become blind for your own errors after working too long on a text. You won't notice your own mistakes. A few days later the text has sunk in a bit. You are better able to read the text as if it were someone else's.
Always stick to the same style. You can write in the I form, one, you, or impersonal. You can use present tense or past tense. Choose either one of these and stick to them. Changes can be confusing and reveal inexperience. I chose the you form, and present tense. I think this is the best style for this site. Direct and personal, as if I were talking to you.
Watch your grammar and spelling. The least you can do is to check it on your text processor. Grab a dictionary for difficult words. If you don't take the trouble to write proper English, people may not take you seriously otherwise. If you don't take care in your use of language, how much do you care about the contents of your story?
Writing is not an easy job. You often will erase more than you eventually write. Take your time to write. Write and rewrite until you are satisfied with it. Not too long or too short, just long enough. Short enough to not to bore people. Long enough for you to say what you have to say.