How to Fade out Custom Unity Shader ?

I have a custom shader which can render texture inside an object (such as : Shpere). But I can't transparent it because unity says there is no _Color property added in that shader. I am not an expert in Unity Shader, so need some help how to transparent my existing shader. Here is my shader code.

Shader "InsideVisible" { Properties { _MainTex ("Base (RGB)", 2D) = "white" {} } SubShader { Tags { "RenderType"="Opaque" } Cull front // ADDED BY BERNIE, TO FLIP THE SURFACES LOD 100 Pass { CGPROGRAM #pragma vertex vert #pragma fragment frag #include "UnityCG.cginc" struct appdata_t { float4 vertex : POSITION; float2 texcoord : TEXCOORD0; }; struct v2f { float4 vertex : SV_POSITION; half2 texcoord : TEXCOORD0; }; sampler2D _MainTex; float4 _MainTex_ST; v2f vert (appdata_t v) { v2f o; o.vertex = mul(UNITY_MATRIX_MVP, v.vertex); // ADDED BY BERNIE: v.texcoord.x = 1 - v.texcoord.x; o.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex); return o; } fixed4 frag (v2f i) : SV_Target { fixed4 col = tex2D(_MainTex, i.texcoord); return col; } ENDCG } } }