Open the compressed file is named Chawg_Keyboard_Layouts.
It contains an installation/setup file also called Chawg_Keyboard_Layouts, double-click it until the installation window opens and then continue with the installation steps.
Go to Control Panel, then open Regional and Languages. Click the Keyboard and Languages tab and click Change Keyboards (click Details on Windows XP).
Then do as shown in the picture. Right-click one of the two keyboards you want to type with. (If the keyboard is not in the small list, click show more to display a list of all keyboards.