I have a 9020 Mt desktop. I bought a xfx Rx 560 graphics card and a second hard drive. The video card needs a 6 pin plug. Where do I get that at?  It says it's rated at 75w so the stock PSU should handle it right?

I also need to buy the mounting brackets for the second HDD. Where can I buy those?

Can I buy any of this on Amazon? I have prime.

I included pictures