It includes information on why you might want to have multiple Gmail accounts.
Instructions in this article apply to Android 2.2 and above and should work with any Android phone.
Adding one or more additional Gmail accounts to your Android phone is a straightforward process.

Tap theGmailicon on the phone’s home screen or find it in the system list.
In the upper-left corner of Gmail, tap themenubutton to display additional options.
Scroll to the bottom of the menu, then tapSettings.

In theSettingspage, tapAdd account.
In theSet up emailpage, chooseGoogle.
That’s because you’re adding a second Google account to the phone by adding this email address.
When it’s done, the Gmail sign-in screen appears.
Either enter the existing Gmail address or selectCreate accountat the bottom of the page.
If you enter an existing Gmail address, pressNextto continue.
When you’re done, the GmailSettingsappears.
The new account is listed below your previous account.
When you give your email address to these sources, they send lots of messages.