To join a meeting on GoToMeeting simply go to http://www.gotomeeting.com as indicated by the green arrow below. Then click on the "Join a Meeting" button as indicated by the red arrow.
Once you have clicked on the "Join A Meeting" you will be presented with the following. In the last half an hour you should of received an email with the nine digit Meeting ID. Type that Id into the input box and click on the "Join" button.
After you click on the "Join" button you will see the following screen. If you are on a laptop and plan on talking using either the laptops build in microphone or have a compute with a headset plugged in click on the "Use computers audio". If you do not plan on talking to the other member of the meeting just click on "I Don't need any audio". It is doubtful that we would be using a phone because of the additional cost.
That is it. You should be part of the meeting. If you have any problems try contacting the Organizer via email.