To install the codec pack, you have to download it from its official website: http://www.codecguide.com/download_k-lite_codec_pack_mega.htm
Use one of the mirrors to download the installation package, then launch it. When it's launched, press Next, then choose the installation mode. Based on your selection, the installer will offer various customization modes. Choose Normal for standard user, then Next. On the next windows, choose the preferred audio and video player, as well as video decoders. I recommend keeping the default options selected, then clicking Next again. On the next window, choose the Hardware Acceleration code. Click the Help button to see which one you need. After selection is done, click Next and select the renderer. The standard EVR should be compatible with most file formats. Accept the changes, then choose the language on your next window and Next again. Based on your configuration, now you have to choose the output audio mode. After you select it, Next and proceed.
Note: Do not install any other offers, therefore click Decline on next windows and uncheck offers.
Finally, press Install, and the codec pack will be deployed along with the selected settings.