Click the Apple Menu and choose System Preferences.
In the Internet and Network section, choose double-click the Network icon.
From the left menu, select the appropriate Modem (Internal Modem or USB Modem).
Enter the Telephone Access number, which is the number your computer dials to connect to the Internet.
If you don't know a local access number, search for one on the front page of the EarthLink Support Center (support.earthlink.net).
Enter your email address in the Account Name field.
Enter your password in the Password field.
Select the check box next to Show modem status in menu bar.
Click the Apply button at the bottom right of the window to save the changes. To connect, click the Connect button on the Network window.