How to call a Stored Procedure in Code First Entity Framework 6

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C#

ASP.NET

C#4.0

entity-framework

I am very new to Entity Framework 6 and i want to implement Stored Procedure in my project. I searched in google deeply but couldn't find any solution in which i can follow the implementation. I have a stored procedure like below.

ALTER PROCEDURE [dbo].[insert_department]
@Name [varchar](100)
AS
BEGIN
INSERT [dbo].[Departments]([Name])
VALUES (@Name)

DECLARE @DeptId int
SELECT @DeptId = [DeptId]
FROM [dbo].[Departments]
WHERE @@ROWCOUNT > 0 AND [DeptId] = scope_identity()

SELECT t0.[DeptId]
FROM [dbo].[Departments] AS t0
WHERE @@ROWCOUNT > 0 AND t0.[DeptId] = @DeptId
END

Department Class

public class Department
{

    public int DepartmentId { get; set; }       
    public string Name { get; set; }

}

modelBuilder 
.Entity<Department>() 
.MapToStoredProcedures(s => 
s.Update(u => u.HasName("modify_department") 
               .Parameter(b => b.Department, "department_id") 
               .Parameter(b => b.Name, "department_name")) 
 .Delete(d => d.HasName("delete_department") 
               .Parameter(b => b.DepartmentId, "department_id")) 
 .Insert(i => i.HasName("insert_department") 
               .Parameter(b => b.Name, "department_name")));

protected void btnSave_Click(object sender, EventArgs e)
  {
          string department = txtDepartment.text.trim();

         // Here i want to call the stored procedure to insert values

  }

My problem is how do i call the stored procedure and pass parameters into it. Please help me out. Thanks in advance.