First you need to find the derivative:
Then, from the equation of the line you are given, you see that the slopes of the normal line is -2 ; and since you want the slope of the tangets, you get the opposite reciprocal of -2, which is m=1/2.
Now you have y', just plug it in the derivative function and find your x.
Then with that, go back to the original equation and find y.
And you have all the ingredients necessary to set a line equation of the normals.