This tutorial provides step by step by instruction for configuring Gmail on Mac OS X Lion Mail App. Click the Mail icon available on Mac Dock or from the Mac Lion Launchpad. This would display the Welcome to Mail window, requesting you to enter the account details as shown below. Enter your Gmail account details and click the Create button.
After connecting with the server and validating the credentials the Account Summary screen would displayed. You can also setup Calendar and Chat module by marking the corresponding check boxes.
Then click the Create button to complete the setup. The above steps can be followed if you setting Mail for the first time on your Mac OS X Lion. In case if you had already created an account want to add one more then click the File menu and select Add Account from the menu list.
This would display the Add Account screen where you can enter the credentials for configuring your second Mail Account.
After entering the details click the Create button and continue with setup as explained earlier.