Access new processors after CPU upgrade

I just upgraded the CPU in my mac pro. Going from a 4 core to a 6. In Configuration i can still only select from 4 processors. How do i get it to recognize all 6? Also does "processors" refer to Cores or threads? Example, would 2 processors mean 2 cores(4 threads) or 1 core(2 threads)? Thanks!

 

You cannot allocate more than 4 CPU cores to a virtual machine if you have Parallels Desktop Standard. You cannot allocate all CPU to a virtual machine.