This is a really simple task, and can only really cost you up to $8.00 (If you have the parts). So, just read along! There isn't much you have to know, only how to solder (It's melting metal, how hard can it be?) and use scissors.
Step 1: Materials and Tools
Alright, for this, you'll only need a few basic things.
--Solder Iron, Solder Wire (Buy it here for $8.00) --NDS Charger, USB Cable (Lite or Launch, Type-A Male) --NDS (Lite or Launch) of course ;D
Also, recommended, you only use the chargers provided by Nintendo. These will last MUCH longer than 3rd party chargers.