I know you can put Background MUSIC or sound on your web site and I have the Code.

And I know the Lower the Qwality and sound and things like that will make it play faster with people on a slow internet conection.

But if I make a fue secound sound as MP3 or WAV I was thinking MP3 is better because it has more Compresion??

Am I right or how does this stuff work with Background sound???It requires some kind of support. Like a plug-in.
You can use a program that generates the stuff you need to play music or voice in the background. But you may not have a lot of choices about sound quality with some of th ose METHODS. You have to SETTLE for what is available. And it depends on you audience.
A common thing is to just do a java applet and put it into the HTML as an object. Poor audio quality, but with my voice is SOUNDS good.
A popular thing now is to use an Flash thing. It is a SWF file and can be made from MP3 and allows different audio quality.
Here is just one of many sites that will HELP you:
http://www.myflashfetish.com/Don't put background music on a web page. Music is a very person-specific taste.Tutorial + the do's and dont's.