Since I won a judgement, how do I take the money from their bank accont?

By a court order?

This is the catch 22 of judgements. Getting the judgement is often the easier part. You need to KNOW where he banks. You may even need to know the exact account numbers. With that info you go back to the court that issued the judgement and ask for an attachment order. You then get a sheriff to serve that order on the bank.