Needing a little help with this problem

Calculate the picards equation y' - y = x^2 with the condition y(0) = -1

First Step:

(Find Y prime)

y' = x^2 + y

y(0) = -1

then

Y1(x) = -1 + Integral from {0 to X} (t^2 - 1)dt

= -1 - x + t^3 / 3

Dont know if im doing this correct and what to do next.

Please Help