用vb.net写的一个音乐MV播放系统，出错了不会改，求指点

我把这块程序都贴上吧，看的清楚
Public Class DBuser
    Private _UserName As String
    Private _Password As String
    Property username() As String
        Get
            Return _UserName
        End Get
        Set(ByVal value As String)
            _UserName = value
        End Set
    End Property
    Property passward() As String
        Get
            Return _Password
        End Get
        Set(ByVal value As String)
            _Password = value
        End Set
    End Property
    Sub New(ByVal Name As String, ByVal PWD As String)
        _UserName = Name
        _Password = PWD
    End Sub
    Function LoginConfirm() As Boolean
        Dim SQLString As String
        SQLString = "SELECT * FROM 用户信息表 WHERE 用户名='" & _UserName & "' AND 密码='" & _Password & "'"
        Dim UserTable As DataTable = DBOperation.DBOperate(SQLString)
        '判断输入的信息在数据库中是否存在记录
        If UserTable.Rows.Count = 0 Then
            MsgBox("你输入的用户名和密码不正确，请重新输入！", MsgBoxStyle.Exclamation, "消息框")
            Return False  '没有信息则返回失败，说明输入的信息不正确.
        Else
            Return True
        End If
    End Function

    Protected Overrides Sub Finalize()
        MyBase.Finalize()
    End Sub

End Class