Resize columns in datagrid

Hi experts,

having difficulty in resizing the columns in a datagrid....working on a project for a CE device. Created a datagrid from a string (lines from file), but am unable to resize these columns...can't find the right thing on internet....everybody is talking about mapping to a dataset....

my code:

Public Class FrmBestellingen
    Public fi As FileInfo
    Public filenaam As String
    Public Cart As New Data.DataTable
    Public dr As Data.DataRow
    Public teller As Integer


    Private Sub FrmBestellingen_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim Files() As String = Directory.GetFiles(Settings.DataPath)
        For Each FileName As String In Files
               fi = New FileInfo(FileName)
            If fi.Name.ToUpper().StartsWith("P") = True Then
                'ignore
            ElseIf fi.Name.ToUpper().StartsWith("DAG") = True Then
                'ignore
            Else
                filenaam = fi.ToString
                filenaam = filenaam.Substring(11, 14)
                ListBox1.Items.Add(filenaam)
            End If
        Next FileName

        Cart.Columns.Add(New Data.DataColumn("Verteg.", GetType(String)))
        Cart.Columns.Add(New Data.DataColumn("EffekLev", GetType(String)))
        Cart.Columns.Add(New Data.DataColumn("Klant", GetType(String)))
        Cart.Columns.Add(New Data.DataColumn(" Datum  ", GetType(String)))
        Cart.Columns.Add(New Data.DataColumn("KollDatum", GetType(String)))
        Cart.Columns.Add(New Data.DataColumn("Artikel", GetType(String)))
        Cart.Columns.Add(New Data.DataColumn("Aantal", GetType(String)))
        Cart.Columns.Add(New Data.DataColumn("Prijs", GetType(String)))
        Cart.Columns.Add(New Data.DataColumn("Omschrijving", GetType(String)))
        Cart.Columns.Add(New Data.DataColumn("Etiket", GetType(String)))
        Cart.Columns.Add(New Data.DataColumn("Info", GetType(String)))
    End Sub

    Private Sub ListBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ListBox1.SelectedIndexChanged
        Dim lntekst As String = ""
        Dim inhoudfile As String = ""
        Cart.Rows.Clear()
        teller = -1
        filenaam = ListBox1.SelectedItem.ToString

        Using sr As New System.IO.StreamReader(Settings.DataPath & filenaam & ".txt")
            While lntekst IsNot Nothing
                lntekst = sr.ReadLine()
                If lntekst Is Nothing Or lntekst = "" Then Exit While
                teller += 1
                dr = Cart.NewRow()
                dr(0) = lntekst.Substring(0, 2)
                dr(1) = lntekst.Substring(2, 4)
                dr(2) = lntekst.Substring(6, 7)
                dr(3) = lntekst.Substring(13, 8)
                dr(4) = lntekst.Substring(21, 8)
                dr(5) = lntekst.Substring(29, 6)
                dr(6) = lntekst.Substring(35, 5)
                dr(7) = lntekst.Substring(40, 8)
                dr(8) = lntekst.Substring(48, 25)
                dr(9) = lntekst.Substring(73, 1)
                dr(10) = lntekst.Substring(74, 25)
                Cart.Rows.Add(dr)
                dr = Nothing
            End While
        End Using
        DataGrid1.DataSource = Cart
    End Sub


Maybe, hopefully, easy to you experts but as I'm still quit a newby...any help is appreciated...

Thx & regards,
Rob