I have a judgement against someone. How do I find this person? When I find this person's bank, do I just walk in the door and hand them the judgement? At the person's employer, who do I go to or how do I get the company to garnish the wages?

If you find where this person banks or works, you have to go back to the court that issued the judgement and request a write of attachment (bank account) or garnishment (employer). You then have the writ served on the appropriate place (usually by a process server or sheriff).

As to finding them, You have to do that on your own, maybe hire a PI.