Ksp calculations: How to prepare a "saturated" solution

The Ksp of Ag2CO3 = 8.1*10^-12
A student wants to prepare a saturated Ag2CO3 (aq) solution from a 3.7*10^-4 M AgNO3 (aq) solution.
What concentration of Na2CO3 (aq) is required?

How do I set this up with the Ksp/molar solubility equation, and what is "saturated"?
(Thank you- I have an exam today!)

when Ksp = Qsp, the solution is saturated. any additional solute added to the system will not dissolve.

Ksp Ag2CO3 = 8.1x10^-12 = [Ag+]^2[CO3 2-]

if the [Ag+] = 3.7x10^-4M, we can determine the [CO3 2-] required
8.1x10^-12 = (3.7x10^-4)^2(x)
x = [CO3 2-] = 5.92x10^-5M

we need 5.92x10^-5M Na2CO3