I use dreamweaver cs4 but i have no idea how to use html5. in dreamweaver?
You should start your learning here: http://www.w3schools.com/html5/default.asp
Any editor support HTML5 just you need to learn the good Doctype.
Like this:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title>HTML5</title>
</head>
<body>
</body>
</html>
If u need more, visit this:http://html5.ugyesen.com/2011/12/html5-dokumentum-tipus-es-head-ujdons agok/ or this: http://www.w3schools.com/html5/default.asp
North America
Europe, Middle East and Africa
Asia Pacific