1. Logging on and signing in - Open your web browser and go to www.gmail.com. Log in with your email address and password.
2. Settings - You will be directed to your inbox by default. In the upper-right corner of the page, you will see a gear icon. Click the gear icon and click Settings from the drop down menu.
3. Settings tabs - When you click on settings, you will see several tabs. Click the tab that says Accounts and Import.
4. Accounts and Import options - Under this set of options, you will notice one section titled Send mail as: Your Name <your email firstname.lastname@example.org>. Under that, you will see Add another email address you own in blue. Click this.
5. Setting up - A pop-up will appear so you can put a name for that email address and the address itself. When you’re finished, click Next. In the text box labeled, enter the password for that email account, then click Add Account. You can now select mail to be sent from that address even though you’re in Gmail.