asign surface shader to material

Thanks people, i learned a lot by following questions & answers around here! But one point i have been somehow missing (also in unity reference) was how to get a surface shader script onto the material i want it for… how to attach / assign it. Its a cull of diffuse shader script i got from here, for my curtain simulation to be double sided visible… if (youcanhelpme) {Thx = a lot;]

Shader "Diffuse" {
Properties {
	_Color ("Main Color", Color) = (1,1,1,1)
	_MainTex ("Base (RGB)", 2D) = "white" {}
}
SubShader {
	Tags { "RenderType"="Opaque" }
	LOD 200

CGPROGRAM
#pragma surface surf Lambert

sampler2D _MainTex;
fixed4 _Color;

struct Input {
	float2 uv_MainTex;
};

void surf (Input IN, inout SurfaceOutput o) {
	fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
	o.Albedo = c.rgb;
	o.Alpha = c.a;
}
ENDCG
}

Fallback "VertexLit"
}

Just give it a proper name, then you can select it like all shaders…

Shader "MyShaders/Diffuse"
{
   [...]
}

man, i am too stupid for shading! Could somebody please tell me where to add the cull off command in the shader script above?!?