Best path to upgrading from OS 10.11.6 to a more recent (not necesarily the latest) Mac OS
I have a 2012 (made in 2014) Mac Mini Server with 2 internal hds - upgraded to SSDs. My main OS is 11.6 because I have some old - and expensive - sw that cannot be updated, like Photoshop 5. On the other hand there are things only available in more recent OS versions that I would like to access, so I was thinking of installing a more recent OS on the 2nd, presently empty 1Tb internal hd and see how it runs. What is the best method of installing a fairly recent OS version on that 2nd internal hd?
Mac mini, OS X 10.11