Protected Sub GridView1_RowDataBound(sender As Object, e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridView1.RowDataBound
        For i As Integer = 0 To GridView1.Rows.Count - 1
            'extract the TextBox values
            Dim lb As Label = CType(GridView1.Rows(i).Cells(0).FindControl("Label1"), Label)
            'Do your excel binding here
            lb.Text = "123"
        Next

    End Sub

    Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        Dim dtTest As DataTable = New DataTable("Test")
        dtTest.Columns.Add(New DataColumn("col1"))
        dtTest.Columns.Add(New DataColumn("col2"))
        Dim dwrTest As DataRow = dtTest.NewRow
        dwrTest("col1") = "123"
        dwrTest("col2") = "456"
        dtTest.Rows.Add(dwrTest)
        GridView1.DataSource = dtTest
        GridView1.DataBind()
    End Sub