Official images for Raspbian Jessie are available to download from the Raspberry Pi website Downloads page.
Do not use Raspbian Lite or NOOBs to install Raspbian Jessie. This causes unexpected results when installing and configuring your Smart-mirror
After downloading the .zip file, unzip it to get the image file (.img) for writing to your SD card.
With the image file of the distribution of your choice, you need to use an image writing tool to install it on your SD card.