Already filed a lawsuit and won. What is the next step to getting money owed from person we sued?

I can't tell you the specifics of Pennsylvania collection law, but every jurisdiction has procedures for collecting on a judgment ranging from taking discovery about the debtor's assets, to garnishing the debtor's income, and executing on the debtor's assets so that they are sold at auction to satisfy the judgment.  I don't know how much is involved, but rather than attempt to carry out these procedures yourself, it may be easiest for you to simply hire a collection attorney, who will represent you in exchange for a share of what he/she collects.