Log into your Gmail account. If you don't have one you can sign up here: http://www.gmail.com
Once signed in click on the Settings link in the top right hand corner.
Select the Forwarding and Pop tab from the settings window.
Select the option called Enable Pop for all mail and click Save Changes
Launch Apple Mail by clicking on its icon in the dock.
Select Preferences from the Mail menu or press Command-, on the keyboard.
Go to the accounts tab and click on the + sign at the bottom left hand corner.
A popup will appear asking you to fill in your account information. Fill in the information applicable to your gmail account and then click Create.
Apple mail will then automatically find and set the correct server information for Gmail. When setup completes you will return to the Accounts tab of Apple Mail Preferences. Your window should look like this:
Close the Preferences window and return to your inbox. It should look like this!
NOTE**: For those interested the manual setup for the servers is:
Username: gmail username (whats before @gmail.com)
Password: gmail password
Incoming Mail Server: pop.gmail.com
Incoming Mail Server Port: 995
Incoming Mail Server Use SSL: Yes
Incoming Mail Server Authentication: Password
Outgoing Mail Server: smtp.gmail.com
Outgoing Mail Server Port: 25
Outgoing Mail Server Use SSL: Yes
Outgoing Mail Server Authentication: Password