there is no need to create a new user in mySQL, just use the default root user.
through google i found this tutorial that walks through getting started with using PHPMyAdmin for creating a database:
I'm a little unsure on what you are having trouble with, are you trying to create the database in PHPMyAdmin? or create the connection to the database in Dreamweaver?
When you say "it's not working" that does not give me anything to go on, please describe in detail how it's not working. do you get error messages? if so what are they?