Press login button.
Type your nick and password. If you would like that password is saved and next time you won't have to type it, check save password field. Press login button. After successful login some of the buttons in BQ main window can be enabled. If you are logging for the first time you will also see help window.
In lower part of window you can see nicks of users that are currently logged to BQ.
After logging to BQ you can start with bidding contest or bidding panel.