wordpress live site in localhost database error

Hey folks,
I have my Site running.

BUt I finaly decided to copy it to my localhost.

I copied the files: I use WAMP on my Windows 7 Professional x64 machine.

I backedup my online database using phpmyadmin, importet it to my local phpmyadmin. When I’m trying to open the page I get the error Message”Error establishing a database connection”

What am I doing wrong there?

kind regards

winam