how to write insert query

[DataContract]
public class Employee
{
  [DataMember]
  public int Id;
 
  [DataMember]
  public string Name;
 
  [DataMember]
  public decimal Salary;
}
 
[ServiceContract]
public interface IService
{
  [OperationContract]
  void AddEmployee(Employee employee);
}

// connect
MyDataCotext db = new MyDataCotext();
 
// generate new record
EmployeeRecord/*(this is what comes from DBContext)  */ emp = new EmployeeRecord();
 
// assign values
emp.Id = Employee.Id
emp.Name = Employee.Name
emp.Salary = Employee.Salary
 
// add to database
db.EmployeeRecords.Add(emp);
db.SubmitChanges();