Here's a problem from a calculus book that has me stumped:

I don't understand a single thing from the suggestion that the book is giving.. I know how to differentiate, I know how to solve for the equation of a line tangent at a point of a curve using point-slope formula, I know that the line that is normal to said line would have a reciprocal slope to the said line. but I don't know what the heck how to deal with this point Q(a,a^2) thing and everything mentioned in the suggestion. How do I attack this problem? Is this easy?