Draw a set of axes and mark them from say -8 to +8 on both axes using 1cm increments.
To plot a point, position yourself at the origin (ie where the axes intersect, ie the point (0, 0)).
The first coordinate (number in the bracket) is the horizontal movement, the second coordinate is the vertical movement.
So for A(-3, -5), move from the origin -3 horizontally (ie 3 to the left) and then -5 vertically (ie 5 units down). That gets you to point A. Mark it with a dot.
Similar for B. Just watch your positives (right or up) and negatives (left or down).
Take a pic of your answer and show us.