Q:

How do I change an HTML site with Javascript?

I am a beginner to Javascript. Sorry for asking here, but I couldn't find a tutorial for this, and I hope someone can point me in the right direction.
I have an HTML page that has an unordered list on it. I have an input form that allows the user to submit a message. When the user submits a message, I want it to be added to the unordered list. This will be a permanent change to the website.
How do I make Javascript interact with the HTML like that?
---- Example:
    <!DOCTYPE html>
<html>
    <head>
        <title></title>
    </head>
    <body>
    <ul>
        <li>example 1</li>
        <li>example 2</li>
    </ul>
        <form>
            <input type='text' name='Message' value="">
            <input type='submit'>
        </form>
    </body>
</html>

A:

The question's a little vague and I think it would be helpful to understand the concepts rather than have the specific code.
What you're trying to achieve, if you just want to manipulate the HTML using javascript, is to have an understanding of how JS can work with the DOM.
You do this by targeting elements.  And you can target them either by their element type (div), a CSS classname, or most commonly by an id tag attribute.
In the example you've got above, when you submit the form you will need to call a function that will target the message input, grab its value.  Then target the unordered list and append the HTML to the end of it containing the new message.
Since you're new, I would recommend learning jQuery.  It'll get you up and running pretty quickly and you won't have to deal with as much diversity in varying browser implementations.

