Display MessageBox inside Module in ASP.Net

How can i display a message box inside a module asp.net

Imports System.Data
Imports System.Data.SqlClient
Imports System.Configuration
Module StremPos
    Dim streamr As String
    Dim conString As String = ConfigurationManager.ConnectionStrings("SMIS2022ConnectionString").ConnectionString
    Public Function Streamposition()
        Using Con As New SqlConnection(conString)
            Con.Open()
            Using Com As New SqlCommand("Select * from streamclassposition", Con)
                Using RDR = Com.ExecuteReader()
                    If RDR.HasRows Then
                        Do While RDR.Read
                            streamr = RDR.Item("stream").ToString()
                            Using Cont As New SqlConnection(conString)
                                Cont.Open()
                                Using cmd As New SqlCommand
                                    cmd.Connection = Cont
                                    cmd.CommandType = CommandType.StoredProcedure
                                    cmd.CommandText = "position"
                                    cmd.Parameters.Add("@ty", SqlDbType.NVarChar).Value = streamr
                                    cmd.ExecuteReader()
                                    Cont.Close()
                                End Using
                            End Using
                        Loop
                    End If
                End Using
            End Using
        End Using
        Return Nothing
    End Function
End Module

ScriptManager.RegisterStartupScript(Me, Me.GetType(), "askConfirmk", "alert('Data Successfully Updated ... !!')", True)