where would negative imaginary be graphed

Here is what Melody is describing....it's known as the  "complex" plane....

http://www.clarku.edu/~djoyce/complex/plane.html

complex numbers can be graphed on a number plane the horizontal axis is the real part and the vertical axis is for the imaginary part

if the Imaginary part is neg the point will be below the real (x) axis.

I'd post a graph but I am on my phone so I can't. :(