Calculating Moment of Inertia

EDIT:
Damn! wrote that in the wrong forum!!
mods please move to introductory physics!
thanks

Hi,
I'm learning by myself physics of rigid bodies , and I find it kinda hard.
Well, I know calculating the moments of Inertia is useless cause You have a table with all the MoI.
This is not a specific problem i ran into but I'll write it anyway:

Homework Statement

Calculate the Moment of inertia of a rotating(about it's center of mass) solid wheel of mass M( assume it's homogeneous)

Homework Equations

I= integral of something :PPP

The Attempt at a Solution

well i just know that the moment of inertia of a ring of mass M is MR^2/2
seems kinda intuitive,I'd like to know how do I (using integrals) calculate the MoI of a solid sphere as stated above.
$I_{ij}(O)=\int_V dV \rho(r) \left( r^2 \delta_{ij} -r_i r_j \right)$
$I_{ij}(O)=\int_V dV \rho(r) \left( r^2 \delta_{ij} -r_i r_j \right)$