M.2 SSD 850 EVO not found on ASRock z97 Extreme6

[Rockit10]

How do I enable the M.2 port on my ASRock Z97 Extreme mother board so that I can use my Samsung SSD EVO M.2 512bg. as a boot drive.
Currently the system does not seem to know it is there.

 

[Suztera]

Check in the BIOS that the M.2 slot is enabled.

 

[Rockit10]

I did that and the M2 slot is enabled.
I really am looking for something more specific in case I am missing something very basic or well hidden.
Exactly what setting(s) are supposed to be enabled and how do I know if it is working?