Spherical Coordinates and Centre of Mass

Wondering if someone could help me get this answer. I don't get spherical coordinates at all. What does the uniform material part mean in terms of delta?

The volume of the region given in spherical coordinates by the inequalities

3 less than or equal to rho less than or equal to 5

0 less than or equal to phi less than or equal to pi/6

-pi/6 less than or equal to theta less than or equal to pi/6

is filled with uniform material. Find the x-coordinate of the centre of mass.

Thanks for any help.

John