All the information you need about the codes can be found here:
http://starmen.net/mother2/guides/wtw2/

And for the heck of it, here's that reaaaally old video on my reaaaally old channel.
https://www.youtube.com/watch?v=pJpDGa2KpiM
Go on, have a look. It'll likely always have more views, but oh well. Not really that big of a deal.