Here is some sample code that I am using this week for my ADO.NET session at Whilfest. It should answer your questions about how work with your data.

Steps involved:
Modify data inside of DataSet as necessary
Call Update method of DataAdapter
Call the AcceptChanges method of the DataSet

Updating Data:

Dim strSQL As String = "SELECT * FROM Authors “ & _
	“Where au_lname='Green'"
Dim sda As New SqlDataAdapter(strSQL, connStr)
Dim scb As New SqlCommandBuilder(sda)
sda.UpdateCommand = scb.GetUpdateCommand()
Dim ds As New DataSet()
Dim dr As DataRow

sda.Fill(ds, "AuthorInfo")
dr = ds.Tables("AuthorInfo").Rows(0)
dr("au_fname") = "Lisa"

If sda.Update(ds, "AuthorInfo") = 1 Then
	ds.AcceptChanges()
Else
	ds.RejectChanges()
End If

Adding New Data:

Dim ds As New DataSet(), dr As DataRow, dt As DataTable
strSQL = "SELECT * FROM Authors Where 0=1"
Dim sda As New SqlDataAdapter(strSQL, cnn)
Dim scb As New SqlCommandBuilder(sda)
sda.InsertCommand = scb.GetInsertCommand()

sda.Fill(ds, "AuthorInfo")
dt = ds.Tables("AuthorInfo")
dr = dt.NewRow()
dr("au_id") = "111-11-1111": dr("au_lname") = "Randell"
dr("au_fname") = "Brian": dr("contract") = 0
dt.Rows.Add(dr)
If sda.Update(ds, "AuthorInfo") = 1 Then
  ds.AcceptChanges()
Else
  ds.RejectChanges()
End If

>Hi,
>
>I created a simple project using windowform and vb.net.
>
>Standard Wizards.
>
>SqlConnection, SqlDataAdapter1 (Employees), SqlDataAdapter2 (JobType), SqlDataAdapter3 (JobTitle) and a DataSet with all 3 tables included in the generate dataset wizards.
>
>Added SearchLastName(Textbox), SearchButton, DataGrid1 to display the results of the search and textboxes, Comboboxes and 5 buttons to the Form for the edits etc. for the detail fields.
>
>The idea here is to:
>
>(1) Type in the lastname and click search, Position the grid to the desired record and click the EDIT BUTTON to edit the textboxes/comboboxes (fields) and then CLICK BUTTON to update (save) changes to the record and to the datasource; Optionaly you can click the CANCEL BUTTON and that would undo the changes that you made to the textboxes etc.
>
>(2) Position the grid to the desired record and click the DELETE BUTTON the selected record.
>
>(3) Click the ADD BUTTON to add a new Record and SAVE BUTTON would add it to the datasource. Also the CANCEL BUTTON would allow to cancel the add record.
>
>What is the proper coding for SQL DataApater and Datasets when a button is clicked to:
>
>ADD a Record to the dataset for Employees table:
>
>EDIT/CHANGE selected record in the dataset for Employees table:
>
>SAVE Edits/Changes selected Record to the dataset for Employees table:
>
>DELETE selected record in the dataset from the Employees table:
>
>CANCEL Edits or Add to the dataset for the Employees table:
>
>
>Thanks
>Roland