[Unanswered] Help with modding

I'm wondering how I would go about making a mod.
It would be like this: You craft an anvil like so:
GIG
I :Where I= Iron blocks, D= Diamond blocks, and G= Gold blocks
DID

When you left click on it you would get an interface like a furnace.
In the top you would put a damaged tool or piece of armour.
In the bottom you would put a hammer, which is created like so:
iSi
s :Where i= iron ingot, S= stone, and s= stick
s
The slot on the right is where the repaired item would come out.
The hammer would also be consumed to repair the item.

I hope someone can help me with the coding.

/topic/214082-minecraft-v18-1-campcraft-smpssp-anvil-modssp/#Anvil
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