You can put this solution on YOUR website! First of all, look at the denominator. It factors as (x-4)(x+3).
So, we know that x=4 and x=-3 cannot possibly be valued because they result in division by zero. They are vertical asymptotes. Horizontal asymptote exists at y=1/1 due to the coefficient of the highest degree of the numerator divided by its counterpart in the denominator (squared terms).
Now, f(0)=0/-12=0 is the y-intercept.
f(x)=0 is the x-intercept.
This is, for the most part, all the information you need to produce the following graph (note that you may want to compute values to determine magnitudes of curves for a more accurate graph):
Note that the vertical lines that this site draws in do not belong in the picture.