you just do.
first log in google talk and click on person who you want to video chat. on side there is a option video call.click on it and enjoy the video call.
You should be able to email them no problem or use the help menu on one of their products.
Download it from: http://www.google.com/talk
Google has many uses. Copy and paste the following URL to see only SOME of its services. And all of them are free! You can upgrade on some of them which costs money, but they don't give you, like,...