When i talk on gtalk person who is speaking with me cannot listen

Gtalk is only available on windows, so it cannot be installed on a macbook air.
Although, you can install the gtalk plugin and chat while logged into gmail from with the browser on your mac.
http://www.google.com/talk/

If you cannot hear the other person then, your the speaker may not configured inSkype.
To configure thespeaker - Open Skype - Tools - Options -Audio Settings - Speakers select your audio card, check the volume slider THEN click on Save.

The person you are talking with needs to put on headphones or turn their volume way down.

Is it your network blocking you from accessing Gtalk? Try web messenger like KarooLark web Gtalk http://karoolark.com/#gtalk

Faking attention - would be pretending to listen to someone who is talking and making them think you are actually interested in what they are saying. Some people fake attention so they will not seem rude to the speaker. Others do it because the person speaking is an authority figure and they do not want to get into trouble. Guy's do it when their girlfriends are babbling and so on.

You want an example of "faking attention"?

My Sister loves to talk. She talks 24/7 and does not stop. The things that she talks about are silly and useless knowlege. I can only tolerate her for small periods of time before the noise irritates me and makes me angry. Sometimes when she is talking about nothing that I want to hear about, my mind wonders and thinks about other things that I am interested in. While my mind in wondering, I no longer hear what she is saying. Allowing my mind to wonder blocks out her speaking and gives me a little break. While my mind is wondering, my eyes and attention seemed fixed on her as if I were listening. I have even learned to say "really" or "umm hmm" whenever she pauses between sentences in order to fake that I am paying attention. When she is finished speaking I have no clue what she thinks that we spoke about? It is a mean thing to do but all of us are guilty of it at some point in our lives.

If you mean Google Voice? It is only available from the USA.

Check your internet connection active or not. If it is active, then do the necessary settings in your GTalk application allowing your application to connect.

that's a problem with software...

try downloading google talk again and install it... even then if you are getting the same problem... its a problem in the Operating system... some file must have corrupted... so re-install OS and install gtalk...

or simple way.. juz login to your gmail id... u have an internal gtalk available... in inbox itself.. hahaha..

Go to your control panel in windows, you can get there from the start menu no matter what version you are on.

In the control panel, double click on Sound. In the new window, click on file and settings... or advanced I cant remember exactly which as I am using vista. There you should be able to select "Recording". Click ok.

Now you should be able to see where it says microphone, with a volume bar and so on. Put a check in the "Mute" box. This will not completely mute the microphone, it should only make it to where you will no longer hear it on your speakers.

Try talking to your friends now... It should work! I hope this helped to fix your problem, if not, let me know and we can try something else.

While speaking to one person, press the "conf" button... Wait for a beep beep, hit 9 then dial the other number... talk to the new person... press "conf" again... talk to everyone