Help Wanted with Integral Word Problem

Hello,

I am not any good with these word problems.

I am struggling with this:

"Find the total mass of a circular region of radius 6 if the density (mass units per unit area) at a point in the region is the sqare of the distance from the point to the center of the circle. (Divide the region into circular shells, i.e., washers.)"

I don't know where to begin, but a circle with radius 6. I can't even determine if this is supposed to be 2-D or 3-D.

Can anyone please help me?