How To create An API in creatio and access in postman

For creating An Api i was tried to create a webservice to retrive an email from employee section  in creatio.it was published without any errors

below is the following code.

namespace Terrasoft.Configuration

{

    using System;

    using System.Configuration;

    using System.ServiceModel;

    using System.ServiceModel.Web;

    using System.ServiceModel.Activation;

    using Terrasoft.Common;

    using Terrasoft.Core;

    using Terrasoft.Web.Common;

    using Terrasoft.Core.Entities; 

    [ServiceContract]

    [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)]

    public class UsrCustomConfigurationService : BaseService {

    

        [OperationContract]

        [WebInvoke(Method = "GET", BodyStyle = WebMessageBodyStyle.Wrapped,

            RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json)]

        public string EmployeeDetails(string Name) {

           // Default result.

            var result = " ";

            // The EntitySchemaQuery instance, addressing the Contact database table.

            var esq = new EntitySchemaQuery(UserConnection.EntitySchemaManager, "UsrEmployee");

           

            var Fname = esq.AddColumn("UsrFullName");

            var eid = esq.AddColumn("UsrEmailid");

             var esqFilter = esq.CreateFilterWithParameters(FilterComparisonType.Equal, "UsrFullName",Name);

            esq.Filters.Add(esqFilter);

            // Receiving query results.

            var entities = esq.GetEntityCollection(UserConnection);

            // If condtion the data received.

             if (entities.Count > 0)

            {

                /* Return the "Id" column value of the first query result record. */

                result = entities[0].GetColumnValue("UsrEmailid").ToString();

                /* You can also use this option:

                result = entities[0].GetTypedColumnValue(colId.Name); */

            }

            // Return result.

            return result;

        }

    }

}

Now, I am trying to access the webservice API from postman. But it was giving an error. I was attaching the image for reference. Whether I followed correct procedure or not?

If any other procdures to retrieve data.please,help us.