Electric field is a vector -- that means that a sum of many electric fields requires vector addition, with arrows. Just adding up the values of kQ/d^2 does not work. (I don't care how many times you say this, someone in your class will forget on a test or quiz.)
The electric field created by a point charge points (hah!) away from a positive charge, and toward a negative charge.
Electric field vectors, like all vectors, are best added by placing them tip-to-tail.
Now consider diagram 2. The top charge still creates a field to the right, but the bottom charge now creates a field down and to the left (toward the negative charge). The vector sum of these fields is in red below: