This gist is for the ConnectCore i.MX6UL starter kit.
If you want to launch linux using a micro SD card, you will need at least a 8GB card.
In order to boot the Digi ConnectCore i.MX6UL from the micro SD first you have to divide the micro SD into 2 partitions. The first one should be FAT32 so it can hold the images and the second one should be ext4 since it is going to have the root filesytem.
You can use any tool like gparted to do this. Once you have the microSD formated you will need to copy the corresponding files to the FAT32 partition. For the starter board (ccimx6ulstarter) the files are:
zImage-ccimx6ulstarter.bin