From the Official Article: Configure Pidgin to connect to Google Talk (with modifications by me):
Once you download Pidgin, you'll need to configure your client to connect to the Google Talk service.
To configure your account:
- Open Pidgin.
- Select Add (under Accounts → Manage Accounts → Add)
Enter the following information in the Add Account window:
Screen Name: your Google Talk username without any @ symbol or domain *content to the left of the '@' symbol).
Server: (or Domain) Enter the portion of your email address after the @ symbol. For example, firstname.lastname@example.org will enter example.com as the server value. (If you're not a Google Apps for Your Domain user, please visit the Google Talk Help Center for instructions.)
Password: we suggest leaving this field blank for increased security, but if you'd like to log in automatically, enter your password
Local Alias: leave this field blank
Remember password: check the box if you'd like Pidgin to remember your password (you won't be prompted to enter it each time you log in, if you select this option)
New mail notifications: check the box if you'd like Pidgin to notify you of unread email in your inbox.
- Click the 'Advanced' tab and select Require SSL/TLS, or sometimes more simply Require Encryption.
- Google doesn't say this, but make sure under "Connect Server:" that talk.google.com. is set.
- Click Save.
You're now ready to connect to the Google Talk service using Pidgin.