How can I record myself with sound from the iSight camera in iMovie?

I've used iMovie before, to record myself on my old Mac, but on my new one, I can record myself, yet there is no sound on playback. I don't know whether it is failing to record sound, or if the sound on playback is muted.

I keep getting referred to this article:

http://support.apple.com/kb/TS2289?viewlocale=en_US&locale=en_US

But it makes no sense to me.

I have checked to see that I have the latest version of iMovie, but I can see no "clock button" or "sound icon" so I simply don't know how to make sense out of what they're saying.

I recently installed Skype, and had a problem with someone hearing me. I had to change the settings in system preferences > sound, and now have both output and input set to internal microphone/speakers. People can hear me on Skype, and I have tried using the soundflower options (I don't understand what they are) but nothing seems to work.

If you know what the problem is, could you possibly include a screenshot, showing me where the buttons are that the Mac article is referring to.

I simply don't see them.