In Gmail, click Settings and select Settings.
In the General tab, scroll to the Language section. Click Show all language options and check the Enable input tools box.
In the Input Tools window, double-click the All input tools field to select an input tool you want. The tool automatically moves to the Selected input tools field.
Click OK.
At the bottom, click Save Changes.

When you enable an input tool, click the Keyboard to turn it on and off, and click the Down arrow to switch between tools.