You need a 5V power supply. If your using a PC you can use one of the power plugs inside that.
Looking at the 4 pin molex plugs. Black is earth, Yellow is 12V and Red is 5V.
So youd hook a Red wire to the map sensors input voltage. And a black to to the earth of the MAP sesnsor.
Run run another wire from earth into the 0V and the signal from the MAP sensor into the signal of the bluebox on one of the 3 inputs AUX1/2/3

The gm sensor I have is a 3 pin one I believe 

A = earth 

B= signal to your dyno 

c= 5v supply 

I just wasn’t sure if the yourdyno had its own 5v supply 

I’ll look into the pc see if I can find a 5v feed 

On my computer iv gotten a molex to sata power adapter. Like the attached picture.
Cut the sata end off it and made a thumb screw pannel on one of the removable pci-e port back plate block offs.

Its a good idea to use a fuse as well so if wire ever burns though or sorts in some way you dont damage the computers power supply.

Yourdyno only have 2 pin, ground and signal. you need 5v supply. then connecto to C. what i did for sensors i use in my dyno, i take out 12v and 5v from PC power supply with connectors. or you can get another power supplier.