Log in to your Gmail account.
Click the gear-shaped icon in the upper right corner of the screen and select the “Settings” option.
Step 3
Click the "Accounts and Import” link at the top of the Settings screen.
Click the “Import mail and contacts” link.
Enter your Yahoo email address and click the “Continue” button. Type your password and click "Continue." Gmail verifies your Yahoo account, then asks you to select your preferred import options.
Check the box next to “Import Mail” and click the “Start Import” button. The emails in your Yahoo account will be forwarded to your Gmail account automatically; however, the process can take up to two days to complete.
Click "OK" when the Finish screen appears.