A simple turn based RPG damage function

So basically i was trying to modify the CodeSampler.com tutorial on weapon dmg to my RPG dmg. So far i have a gui that comes up when you collide with an object. (its an ant) It has an attack button. I dont know what to call from the command of the button to get my damage function to run...

I have className = HP; in the datablock StaticShapeData(Ant) section also

function HP::Damage(%this, %object, %sourceObject, %damage)
{

echo( "Function HP::Damage has been called");
}

This is my function because i didnt want to get ahead of myself, and i just wanted to get it called.

function ShapeBase::damage(%this, %sourceObject, %damage)
{
// All damage applied by one object to another should go through this
// method. This function is provided to allow objects some chance of
// overriding or processing damage values and types. As opposed to
// having weapons call ShapeBase::applyDamage directly.
// Damage is redirected to the datablock, this is standard proceedure
// for many built in callbacks.
%this.getDataBlock().damage(%this, %sourceObject,%damage);
}

I also have this in server/shapebase.cs. I dont really understand why but it looks like it belongs there...

So my questions:
1:Should i make another function in somewhere to call my dmg function?
2:How should i call it from the command field in the GUI?
3:Are the arguments %this and %object values that you dont have to enter? it seems like they didnt put those 2 in when they called the funtion.

Could someone please help me or point me to a good resource? Im lost as hell here. I ordered the GG book but it hasnt come yet and im stuck =/

P.S. I see now that i forgot %object in the shapebase part, but it prolly wouldnt have helped because i was guessing commands to put in E.G. Damage(%client.player, 20); which crashed the game pretty quick lol.