Can someone explain how to set this up;

Find the moment of inertia about the z-axis of a this shell of constant density cut from the cone 4x^2+4y^2-z^2=0, z is greater than 0 by the circular cylinder x^2+y^2=2x

The formula for moment of inertia is:

I=double surface integral of (x^2+y^2)density ds

-How do you know which is the surface?