怎么在vb.net2005中，对数据集中的数据表的某行某列的值进行取出和修改

Dim myconn As New OleDbConnection
Dim myda As New OleDbDataAdapter
 myconn.ConnectionString = "provider=microsoft.jet.oledb.4.0;data source=db1.mdb"
 Dim myda As New OleDbDataAdapter("select * from 商品数据库 ", myconn)
 Dim mycmdbuilder = New OleDbCommandBuilder(myda)
        myda.Fill(myds, "商品数据库")
        Dim mydv As New DataView(myds.Tables("商品数据库"))
        myconn.Open()
假设myds.Tables("商品数据库")表有n（n>=10）行，现在我想取出和改变第五行第五列的值该怎么做？越简单越好