Wait.. do you do MX2 (your signature)?
|z| means the displacement of the complex number, z, from the origin.
Similarly, by shifting it upwards 1 unit, |z - i|, means the displacement of the complex number, z, from 1 unit above the origin, i.e. (0, 1).
Same thing with |z - 1|, just meaning the displacement of the complex number, z, from 1 unit to the right of the origin, i.e. (1, 0).
First look for the region where equality holds, i.e. the displacement from |z - 1| and |z - i| are equal. You find that this is y = x (the perpendicular bisector of the chord between (1, 0) and (0, 1) ).
Then you determine whether it will be above or below the line by testing a point seeing if it satisfies the condition.