How to add another ssd or Hdd

Hello, 

I have a dell optiplex 7020. I have 2 hdd and 1 ssd. The question is: is it possible to add 1 hdd and if possible 1 ssd to the system that has already a 500gig hdd 3,5 inch. The other hdd is also 3,5 inch. I have found the 3 sata ports but I found only one port for the the large conector that goes in the hdd. But how do I then get power to the other hdd and if possible ssd. And where can I put the second hdd?