I want to deploy web service on IIS 7.5 with framework 4.6.1

Question

I have created a web service in vs2013 that retrn sum of 2 numbers

public class SampleWebService : System.Web.Services.WebService
   {

       [WebMethod]
       public int SumOfNums(int First, int Second)
       {
           return First + Second;
       }
   }

and build it with framework 4.6.1. 

 

 

and now i deployed it on IIS 7.5 but it gets error

how to fix this error