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<string>(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.