You need to take out the SD card and use a computer for image burning, and it can be roughly divided into 3 steps:
1. Download the OS iamage
2. Format the memory card
Using SDFormatter software to format the SD card.
You can download this software from the download link at the bottom of this comment.
3. Install the image
Using Win32DiskImager software to install the iamge, which is very easy to operate.
You can download it from the download link at the bottom of this comment, too.
After you have burned the image, inserting the memory card into the Raspberry Pi of CrowPi2, and then turn it on.
If you want to install emacs, check this link for package updates: