Vector calculus: divergence theorem! help!

Using the divergence thm, evaluate the following equation

$\displaystyle \int\int_{s}(a^{2}x^{2}+b^{2}y^{2}+c^{2}z^{2})^{-1/2}dS$

where S is the surface of the ellipsoid $\displaystyle ax^{2}+by^{2}+cz^{2}=1$

I am suck on this question because I have only done them for spheres.

I am not sure of how to get the normal and then what to do from there. I know it seems like I haven't done a lot on this question, but I am struggling to see how this question would be done.