Explain how the graph of y = f(x + h) can be obtained from the graph of
y = f(x) when h > 0 , and also when h < 0.

When you replace x by x + h and h is positive, then the addition of h to
x will cause the values of x to have to be chosen h units less to offset the
addition.  That will cause all the points to move left by h units.

When you replace x by x + h and h is negative, then that's really a 
subtraction of |h| from x and will cause the values of x to have to be 
chosen |h| units more to offset the subtraction.  That will cause all the
points to move right by |h| units. 

Edwin