L2J Server

I have searched the forums for quite a bit so as always, when I don't find something I'm looking for I post it.

Where can I find the core part (or possibly DP Part) to add rewards when someone levels up and completes a class upgrade.

What I want to do is the following:
1st Class Change you get some Adena.
2nd Class Change you get some Adena and Ancient Adena.
3rd Class Change you get some Adena and a Giant's Codex.

Thank you for any help with regards to this topic

Latest I found out...

I could possibly do changes here:

net.sf.l2j.gameserver.model.actor.instance - > L2ClassMasterInstance

However I have nothing that I could think of to work with so I can make it so it gives Adena on changes.

Again, any help appreciated....

Just take a look at l2jfree classmaster, you might make something out by looking at their code.