Just follow the below instructions, and add language on your computer:

1.) Click Start, then Control Panel.
2.) In the dialog that pops up, click “Date, Time, Language, and Regional Options”, or in classic view, simply “Regional and Language Options.”
3.) Click the tab labeled “Languages”.
4.) Click “Add…” and select your language from the drop-down box. If it prompts for a keyboard layout, select the applicable one. (Most likely QWERTY or DVORAK.)
5.) Press “OK” to finalize the change.
6.) When you want to switch languages, either press left Alt + Shift until the little box on the taskbar changes.
7.) You can also add a key combination for each language by selecting “Key Settings” in the Input Languages dialog. (Step 2).

[Via Wikihow]