The link to the login page should be sent to you in a confirmation email (from GotoMeeting) once you register for a webinar. On the day of the webinar, about 15 minutes before the webinar, you will be able to login to the webinar from this page and wait until the session begins. You will need to enter your name and email address that you registered with.
Audio for the webinar will be streamed via your computer speakers. Make sure that your computer speakers are on and test your system to see if you can receive audio via Macromedia Flash.