Changing your Gmail address requires you to create a brand new Gmail account. However, using a new account does not mean losing your data, as Gmail lets you import existing mail and contacts to your new account as well as automatically receive new mail sent to your old account.
Creating a New Account
Log out of your current account, visit the Gmail home page and select Create an account.
Enter your First and Last Name and select a New Email Address and a Password. Enter your Birthday, select your Gender and type in your Mobile Phone Number.
Select either No Thanks or Create Your Profile, depending on whether you want to create a new Google+ profile in addition to your Gmail account.
Click Continue to Gmail to finish creating your new account.
Importing Your Emails
Log out of your new account and log in to your old Gmail account. Select the cog-shaped icon to open the main menu and select Settings.
Open the Forwarding and POP/IMAP tab and select Enable POP for all mail. Click the Save Changes button. Click your profile picture thumbnail (or generic person icon) in the upper right corner of the window and click Log Out.
Log in to your new account, open the main menu with the cog-shaped icon and select Settings. Open the Accounts and Import tab and click the Add a POP3 mail account you own link.
Enter your old email address in the field and click Next Step.
Type your old email address in the Username field and the password associated with that account in the Password field. Click Add Account to start the importing process.
Importing Your Contacts
Log in to your old account, open the Gmail menu and select Contacts.
Open the More menu and select Export.
Select Google CSV format and click Export to download the file to your hard drive. Log out of your account.
Log in to your new account, open the Gmail menu and select Contacts. Open the More menu and select Import.
Click Browse, select the CSV file on your hard drive and click Import to finish importing your old accounts to your new account.