My company uses WebEx for instant messaging and online meetings, which looks like it has similar features to GoToMeeting. I'll describe my process and hopefully it will help.
You go to the site and enter meeting info. The system sends you (the host) an email with all the log in info which you can forward to participants. You can also enter email addresses when you set up the meeting and the system will send out the invites. If you're dealing with a global audience, be mindful of any time zone differences.
Our setup allows the meeting to run until the host kills the meeting.. not sure if that's a common feature or not.
Inside the meeting, you will have an interface that allows you to "give control" to anyone for desktop sharing, presentations, video, etc. There is also a window that shows attendees, and a window with a chat box. Probably other things, but those are the ones I use most.
Everyone will probably need to install some kind of software before the meeting starts, so if you can walk them thru it beforehand, I'm sure they will appreciate it.