"how to design a simple website that will just display text,
graphics and upload video using AS3"
Ok, display text and graphics, easy. Upload video, not as
easy. Upload video will require some backend code, like PHP, so it
goes beyond Flash. The Flash part is fairly easy, but only if you
understand the basics about event listeners (sounds like you do),
objects, and making URL requests.
First of all, if you are making "simple website" I recommend
that you:
1. Open Publish Settings, go to the Flash tab, and click
"Permit debugging" - this will give you line numbers when an error
occurs
2. In the same tab, click "Settings..." next to the
"ActionScript 3.0" dropdown and uncheck "Strict Mode" -- this will
make working with simple code in the timeline easier
3. Recognize that with AS3, development will take you longer
than AS2. You probably won't see benefits that justify the added
development time for using AS3 vs AS2, but it will be helpful if
you intend to make more complex things in the future. Consider your
goal.
To create text you can just use the text tools in Flash. If
you want load text into Flash dynamically (good idea) using an .xml
file or .txt file with url variables, then in AS3 you should learn
about:
URLLoader
URLRequest
XML
Textfield.text and Textfield.htmlText
Giving Textfields and symbols instance names so they can be
referenced in code
addEventListener and events such as "progress" and "complete"
to react to stuff you load
For graphics, you can just add them in Flash as well. If you
want to load in graphics at runtime (also a good idea when
reasonable) then you should also look into the Loader class.
For uploading video, you will need to at least look into the
FileReference class, which allows you use browse() to let the user
pick a file off their system with a dialog box, and after adding
event listeners to listen for when the user selects something, you
use upload() to send it to a server. The server then needs to do
something with it (write it to a file on the server, for instance),
which they have some sample PHP code for in the help docs.