Explicit evaluation of perturbation equations (summing and differentiating)

[Jamal Shafiq]

I have defined a manifold along with a metric and perturbation. Using Bloomfield's tutorial on perturbation theory, I've been able to compute perturbations of the Ricci tensor to all orders with ExpandPerturbation, and Perturbed. How do I now plug in a specific background metric, and have xAct carry out all the summations and derivatives in the perturbation equations explicitly? Ideally, I'd then like to impose an ansatz for the perturbation and gauge fixing condition.