Upgrade 3TB drive to RAID 1 using 2nd 3TB drive

Just bought a 2nd 3TB drive and would like to convert/upgrade so that it acts as a RAID 1 setup: anything changed on the 1st drive gets changed on the 2nd (mirror). Any tips/suggestions/warnings/ANYTHING that will help with a successful installation would be much appreciated! Thanks in advance.
Cc

You cannot setup a “raid” with the entry level single drive My Cloud units. What you can do is connect an external USB drive to increase storage space and use as a backup location for the WD My Cloud Dashboard SafePoint backup option.

There are various non WD sanctioned methods of using SSH to copy data from the My Cloud to an external USB connected to the My Cloud.