How to use where clause with two parameters

i am trying to use the select clause with two parameter

please help

    Private Sub BindDataList200()
        Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
        Using con As New SqlConnection(constr)
            Using cmd As New SqlCommand()
                cmd.CommandText = "SELECT Id, Name,classes,subject FROM tblFiles WHERE Classes ='" & Classes.SelectedValue & "'" & "And" & Subject ='" & subject.SelectedValue & "'"
                cmd.Connection = con
                con.Open()
                DataList1.DataSource = cmd.ExecuteReader()
                DataList1.DataBind()
                con.Close()
            End Using
        End Using
    End Sub