How to make changes directly in database ? I read jm tutorial about RetrieveData

Code:
Private data As DataRow

Public Sub New(ByVal data As DataRow)

InitializeComponents()

Me.Data = data
Me.txtRecord1.Text =  data("FirstName").ToString()
Me.txtRecord2.Text =  CStr(data("LastName"))

End Sub

Private Sub Edit_Click(ByVal .....) Handles .....

Dim dataRow As DataRow
Dim objDataTable As DataTable

dt = DirectCast(Bank.DataSource, DataTable)
dataRow = dt.NewRow()
dataRow = dt.Rows(Bank.CurrentRows.Index)

End Sub
I dont know how to make update it in database
Code:
dt.Update("Bank")
Nothing change