pdf Transformation

Ok Heres the problem.

A random variable X has the pdf fx(x) = 1/2, -1 <= x <= 1, 0 otherwise. The random variable Y has the relationship y = x^3 + 1. What is the probability density function for Y?

I cant for the life of me figure this out. Ive already spent 3 hours (this is suppose to be review but I cant remember doing it). It involves taking the transformation of fx(x) correct?

Any help would be greatly appreciated.