Susan, if you read toward the bottom of Cheryladay's auction descriptions it offers the insurance and says the cost of it. You would have to let her know that you want it added.
It covers your package from loss or damage, however, from what I've read there are a few ifs, ands, or buts to it; it's not as simple as if your package is lost/stolen you get a refund or if the contents of the package is damaged/ destroyed you get a refund. If USPS considers the items not packaged properly they will deny the claim. Also,you only get purchase price refunded and not shipping