What the different between Google Talk and others Instant Messenger / Messaging Service? Though many of others IM services also used XMPP / Jabber Protocol just like GTalk (Facebook Chat, iChat also used XMPP Protocol), but the GTalk has an ability to store online all the log of Chat in your Gmail Account.
Let forget about it, we wanna discuss how to used (first step) Google Talk in Samsung Galaxy S Captivate aka Samsung SGH i897. Here the steps that you should do:
First from Home screen of the Captivate Select (by touching it) [ Means, Applications then Talk).
Press “Next” button and you are ready to used Google Talk with your google account: Enter Username and Password, then press “Down” navigation, and the last Press “Sign in“. Done!
If you do not had Google Account, you can make it by Touch (click) Create then do the rest!
Source: Samsung Galaxy S Captivate SGH i897 User Manual