How to pay creditors?

Soooo I owed the hospital $500 after giving birth but never ended up paying it. They sent me multiple notifications but I never got around to paying it as my hubby was laid off and I was unemployed. But now that I have the money, how do I find out who the creditor is so I can pay them? The last notice I received from the hospital was several months ago. I haven't received any paperwork, bills or emails from either the creditors or the hospital. Someone told me it's be listed on the bottom of my credit report. But it's not?