Determine where the graph of the given function is concave upward and concave downward. Find the coordinates of all inflection points.

f(x)=x^3+3x^2+x+1

My book has the answer:

up is [-1, infinity)

down is (- infinity, 2]

inflection points (-1,2)

I know you have to find the first and second derivative which is

f'(x)=3x^2+6x+1

f''(x)=6(x+1)

I just don't know where to go from there..Thanks!