Using Connection String from App.Config

[FastEddie]

For the very first time I am using a SQL file that is not actualy from the server. I am using a local sql datbase. I have added the connection string to my app.config file but now I am not sure how to use it in code

my config string is named MateCare

Private Sub AddPatient()
        Dim con As String = ConfigurationSettings.AppSettings("MateCare")
        Dim strSp As String = "InsertPatient"
        Dim cn As SqlConnection = New SqlConnection
        Dim cmd As SqlCommand = New SqlCommand(strSp, cn)
        cn.ConnectionString = con
        Try
            cn.Open()
            With cmd
                .CommandType = CommandType.StoredProcedure
                .Parameters.Add("PatientID", _
                    SqlDbType.Int).Direction = ParameterDirection.Input
                .Parameters("PatientID").Value = txtPatientID.Text
            End With
        Catch ex As Exception
            MessageBox.Show(ex.Message & vbNewLine & _
            ex.Source, "ExecuteStartStop Dates", MessageBoxButtons.OK)
        End Try
    End Sub