first, you need the music file (or webcast) to be on the internet. For that, it has to have a http:// adresss.
All you have to do is upload your file onto a webspace server that allows offsite linking and voila, the file is online.
Now, here is what I have put on my page:
<embed src="http://www.ifrance.com/TuxMan/allwant.mid" autostart="false" height="15" width="200">
"embed" here means : Ok, I graft a media file in my page here.
"src" is for the source, the http:// adress I talked about.
"autostart" is a value that is either true(on) or false(off). I set it to false so the music will not start automatically. I let people the choice to hear it or not
"height" and "width" are there so the quicktime buttons are well centered and to prevent some white spaces.
There are other properties that can be set too, but they are a little numerous to show here.
As for the customs avatars and signature, this is done with a photo editing program such as photoshop or Paint Shop Pro. Photoshop CS can be found at your local specialized software merchant, or you can find cheap "second hand copy" on the internet. Paintshop Pro on the other hand has a free 90 day trial on their web site.
Many tutorials for both those programs can be found on the internet. I won't post actual guide to modify an image because the limits are up to your imagination.