Windows 8 users can change the keyboard input method by following different ways.
If you are in Windows 8 desktop then the taskbar would provide option to change the keyboard as shown below.
Using this option, you can pick your preferred Keyboard languages.
Windows 8 Sidebar
Launch Windows 8 sidebar and click the label with your current keyboard language. This should list down the available Keyboard option as shown below.
The quickest method of all is to use the keyboard shortcut, Windows Key + Space bar and this would act as toggle switch for changing from one keyboard language to another.