How to add a second SSD and turn them into a raid 1 array

[Enquiries]

I'm trying to set up a new DS1821+

Tray
1) 2TB SSD [DSM + VMs, Containers and user data]
2) Space for second 2TB SSD [Which I now have]
3 to 6 8TB 3.5inch HDD [Main volume.
7 Space for future.
8) 4TB HDD for Surveillance station recordings.

DSM 7.1 is installed. I would like to add a second 2TB SSD in tray 2 and turn both SSDs into a raid 1 for redundancy.

What's the best route to achieve this? Note: there is no data on any of the other disks.

Thanks in advance,
Peter.