รบกวนสอบถามเรื่อง app.config ครับ การใช้ (VB2008) ใช้ยังไงครับ sql server 2005 ครับ

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <!--<configSections>
    </configSections>-->
    <connectionStrings>
        <add name="Project_RFIDConnectionString"
            connectionString="Data Source=COMSCI-PC\SQLEXPRESS;Initial Catalog=Project_RFID;Persist Security Info=True;User ID=sa;Password=root"
            providerName="System.Data.SqlClient" />
    </connectionStrings>
    <system.diagnostics>
        <sources>
            <!-- This section defines the logging configuration for My.Application.Log -->
            <source name="DefaultSource" switchName="DefaultSwitch">
                <listeners>
                    <add name="FileLog"/>
                    <!-- Uncomment the below section to write to the Application Event Log -->
                    <!--<add name="EventLog"/>-->
                </listeners>
            </source>
        </sources>
        <switches>
            <add name="DefaultSwitch" value="Information" />
        </switches>
        <sharedListeners>
            <add name="FileLog"
                 type="Microsoft.VisualBasic.Logging.FileLogTraceListener, Microsoft.VisualBasic, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL"
                 initializeData="FileLogWriter"/>
            <!-- Uncomment the below section and replace APPLICATION_NAME with the name of your application to write to the Application Event Log -->
            <!--<add name="EventLog" type="System.Diagnostics.EventLogTraceListener" initializeData="APPLICATION_NAME"/> -->
        </sharedListeners>
    </system.diagnostics>
</configuration>

Imports System.Data
Imports System.Data.SqlClient
Imports System.Configuration
Class LogInFrom
    Public pUser_id As String = ""
    Public pPassword As String = ""
    Dim strConnString As String = ConfigurationManager.GetSection("Project_RFIDConnectionString")
Private Sub logIn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles logIn.Click
        Dim objDialogResult As New DialogResult()
        If CheckBox_admin.Checked Then

            Dim objConn As New SqlConnection
            Dim objCmd As New SqlCommand
            Dim strSQL As String

            'strConnString = "Data Source=COMSCI-PC\SQLEXPRESS;Initial Catalog=Project_RFID;Persist Security Info=True;User ID=sa;Password=root"
            objConn.ConnectionString = strConnString
            objConn.Open()

            Dim intNumRows As Integer
            strSQL = "SELECT COUNT(*) FROM ADMIN WHERE ADM_USERNAME = '" & Me.userName.Text & "' AND ADM_PASSWORD = '" & Me.password.Text & "' "
            objCmd = New SqlCommand(strSQL, objConn)
            intNumRows = objCmd.ExecuteScalar()

            If intNumRows > 0 Then

                Dim frm As New Form_Admin
                frm._strUser = Me.userName.Text
                frm.LoadInfor()
                frm.Show()

                Me.Hide()
            Else
                objDialogResult = MessageBox.Show("คุณไม่สามารถลงชื่อเข้าใช้ระบบของผู้ดูแลระบบได้ กรุณาตรวจสอบข้อมูลอีกครั้ง", "Login Fail", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1)
                userName.Clear()
                password.Clear()
                userName.Focus()


            End If
            objConn.Close()

            objConn = Nothing
        Else
            Dim objConn As New SqlConnection
            Dim objCmd As New SqlCommand
            Dim strSQL As String

            'strConnString = "Data Source=COMSCI-PC\SQLEXPRESS;Initial Catalog=Project_RFID;Persist Security Info=True;User ID=sa;Password=root"
            objConn.ConnectionString = strConnString
            objConn.Open()

            Dim intNumRows As Integer
            strSQL = "SELECT COUNT(*) FROM ACCOUNT WHERE USERNAME = '" & Me.userName.Text & "' AND PASSWORD = '" & Me.password.Text & "' "
            objCmd = New SqlCommand(strSQL, objConn)
            intNumRows = objCmd.ExecuteScalar()

            If intNumRows > 0 Then

                Dim frm As New Form_User
                frm._strUser = Me.userName.Text
                frm.LoadInfor()
                frm.Show()

                Me.Hide()
            Else
                objDialogResult = MessageBox.Show("ชื่อผู้ใช้หรือรหัสผ่านไม่ถูกต้อง กรุณาลองใหม่ หรือติดต่อผู้ดูแลระบบ", "Login Fail", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1)
                userName.Clear()
                password.Clear()
                userName.Focus()

            End If
            objConn.Close()
            objConn = Nothing
        End If
    End Sub