Configure Mozilla Thunderbird for your GMail account

Enable POP in your Gmail account.
Open Thunderbird, and select Email account from the splash dialog box and click "Next".
Enter your full name in the Your Name field. Enter your full Gmail email address (username@gmail.com) in the Email Address field, and click "Next".
Select POP as the type of incoming server you are using. Enter "pop.gmail.com" in the Incoming Server field, and click "Next".
Enter your Gmail username (including '@gmail.com') in the User Name field, and click "Next".
Enter a name for your email account in the Account Name field, and click "Next".
Verify your account information in the dialog box, and click "Finish".
Go to Edit > Account Settings from the Menu bar.
Select Server Settings listed beneath your new account.
Check the box next to "Use secure connection (SSL)" and ensure that 995 appears in the Port field.
Select Outgoing Server (SMTP) listed beneath your new account.
Enter "smtp.gmail.com" in the Server Name field under Outgoing Server (SMTP) Settings. and enter 587 in the Port field.
Check the box next to Use name and password and enter your Gmail username (including '@gmail.com') in the User Name field
Select "TLS" under Use secure connection and click "OK".
That's all! Thundebird is all configured to serve your newly added account.