There are a couple reasons why you're having trouble joining your meeting.
How to Join a Meeting
Get Ready for your First Meeting
Join a Test Session
Compare Join Methods
Find your Optimal Connection Settings (Windows)
System Requirements for Attendees
System Requirements for Organizers
I can't join my session
Why isn't the download working?
Why can I hear audio but not see the presentation?
Why can I see the presentation but not hear the audio?
What are the system requirements for using the desktop app?
What are the system requirements for using the Web App?
Which method will I use to join my session?
Why do I get a "could not connect" error when I try to join a session?
Do I need an account to join a session as an attendee?
How do I configure GoToMeeting to work with firewalls?