You don't need a guide, its pretty self-explanatory. You're basically going to use the homebrew application Daybreak which comes bundle with Atmosphere. If you don't have it, you can download it from the
official Atmosphere GitHub page. The second thing you will need to download are the firmware files of the firmware you wish to update to. Since these are copyrighted material, they cannot be linked on this site but rest assured they are readily available on the Internet. Once you have both on your SD card, its as simple as launching Daybreak and navigating to where you put the firmware files.