Can anyone help me change this simple diffuse shader so it works with a dynamic light instead of the sun?

I know I need to use "vecLightPos[1]" to create the eqivalent of "vecSunDir", but how?
Thanks for any help!

Code:

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/***********************************************************************************************
/	Copyright 2006	by Taco Cohen. All rights reserved							
/***********************************************************************************************/

/***********************************************************************************************
/	Global Variables:
/***********************************************************************************************/
// Tweakables:
static const float AmbientIntensity	= 1.0f;					// The intensity of the ambient light.
static const float DiffuseIntensity = 1.0f;					// The intensity of the diffuse light.
static const float4 SunColor = {0.9f, 0.9f, 0.5f, 1.0f};	// Color vector of the sunlight.

// Application fed data:
const float4x4 matWorldViewProj;	// World*view*projection matrix.
const float4x4 matWorld;			// World matrix.
const float4 vecAmbient;			// Ambient color, passed by the engine.
const float4 vecSunDir;				// The sun direction vector.
 
texture entSkin1; 							// Color map. 
 
sampler ColorMapSampler = sampler_state		// Color map sampler.
{
	Texture = <entSkin1>;
	AddressU  = Clamp;
	AddressV  = Clamp;
};
 
/***********************************************************************************************
/	Vertex Shader:
/***********************************************************************************************/
void DiffuseVS(in float4 InPos: POSITION,
				in float3 InNormal: NORMAL,
				in float2 InTex: TEXCOORD0,
				
				out float4 OutPos: POSITION,
				out float2 OutTex: TEXCOORD0,
				out float3 OutNormal: TEXCOORD1)
{
// Transform the vertex from object space to clip space:
	OutPos = mul(InPos, matWorldViewProj);
	
// Transform the normal from object space to world space:
	OutNormal = normalize(mul(InNormal,matWorld));
	
// Pass the texture coordinate to the pixel shader:
	OutTex = InTex;
}


/***********************************************************************************************
/	Pixel Shader:
/***********************************************************************************************/
float4 DiffusePS(	in float2 InTex: TEXCOORD0,
					in float3 InNormal: TEXCOORD1) : COLOR
{
	// Calculate the ambient term:
	float4 Ambient = AmbientIntensity * vecAmbient;
	
	// Calculate the diffuse term:
	float4 Diffuse = DiffuseIntensity * saturate(dot(-vecSunDir, normalize(InNormal)));
	Diffuse *= SunColor;
	
	// Fetch the pixel color from the color map:
	float4 Color = tex2D(ColorMapSampler, InTex);
	
	// Calculate final color:
	return (Ambient + Diffuse) * Color;
}

/***********************************************************************************************
/	Technique:
/***********************************************************************************************/
technique DiffuseTechnique
{
	pass P0
	{
		VertexShader = compile vs_2_0 DiffuseVS();
		PixelShader  = compile ps_2_0 DiffusePS();
	}
}

 

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