Begin by observing that the denominator must NEVER equal zero, so x cannot equala 6. There is an asymptote at x=6. Graph a few points (values of x close to 6 will be most effective!) to see what it looks like or use a graphing calculator:
If x = 0, then f(x) = 6/36=1/6
If x=3, then f(x) =6/9=2/3
If x=4, then f(x)=6/4=3/2
If x=5, then f(x=)6/1=6
If x=7, then f(x)=6/1=6
If x=8, then f(x) =6/4=3/2
etc.