How to make shader receive shadows

Hi All, I've been searching and searching but can't figure out how to make this shader I've been pieces together to receive shadows. This is a toon shader with a light ramp.

If anyone has any ideas that would be amazing!

Thank you, below is the shader.

 Shader "Unlit/Toon1"
 {
     Properties
     {
         _MainTex("Texture", 2D) = "white" {}
     _Treshold("Cel treshold", Range(1., 20.)) = 5.
         _Ambient("Ambient intensity", Range(0., 0.5)) = 0.1
 
         _Color("Color", Color) = (1,1,1)
     }
         SubShader
     {
         Tags{ "RenderType" = "Opaque" "LightMode" = "ForwardBase" }
         LOD 100
         Pass{
         Lighting Off
         ZWrite On
         Cull off
         SetTexture[_]{
         constantColor[_Color]
         Combine constant
 
     }
     }
         Pass
     {
 
         CGPROGRAM
 #pragma vertex vert
 #pragma fragment frag
 
 #include "UnityCG.cginc"
 
         struct v2f
     {
         float4 pos : SV_POSITION;
         float2 uv : TEXCOORD0;
         float3 worldNormal : NORMAL;
     };
 
     float _Treshold;
 
     float LightToonShading(float3 normal, float3 lightDir)
     {
         float NdotL = max(0.0, dot(normalize(normal), normalize(lightDir)));
         return floor(NdotL * _Treshold) / (_Treshold - 0.5);
     }
 
     sampler2D _MainTex;
     float4 _MainTex_ST;
 
     v2f vert(appdata_full v)
     {
         v2f o;
         o.pos = UnityObjectToClipPos(v.vertex);
         o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
         o.worldNormal = mul(v.normal.xyz, (float3x3) unity_WorldToObject);
         return o;
     }
 
     fixed4 _LightColor0;
     half _Ambient;
 
     fixed4 frag(v2f i) : SV_Target
     {
         fixed4 col = tex2D(_MainTex, i.uv);
     col.rgb *= saturate(LightToonShading(i.worldNormal, _WorldSpaceLightPos0.xyz) + _Ambient) * _LightColor0.rgb;
     return col;
     }
         ENDCG
 
     }
     }
     FallBack "Diffuse"
 }