data grid header width changing

how to change the width of the datagrid header text ...
and the width of the column

VB Code:

'returns a datatable  sqlDA.Fill(ds, "DataSet")
        DataGrid1.DataSource = dbMgr.getInstance.GetTableData(l_sqlstmt).Tables(0) 
 
        Dim l_dgts As New DataGridTableStyle
        l_dgts.MappingName = "DataSet"
 
        Dim l_aCol1 As New DataGridTextBoxColumn
        Dim l_aCol2 As New DataGridTextBoxColumn
        Dim l_aCol3 As New DataGridTextBoxColumn
        Dim l_aCol4 As New DataGridTextBoxColumn
        Dim l_aCol5 As New DataGridTextBoxColumn
 
        With l_aCol1
            .MappingName = "GRNNum"
            .HeaderText = "GRNNo"
            .Width = 43
        End With
 
        With l_aCol2
            .MappingName = "GRNDate"
            .HeaderText = "Date"
            .Width = 65
        End With
 
        With l_aCol4
            .MappingName = "Name"
            .HeaderText = "Name"
            .Width = 85
        End With
 
        With l_dgts.GridColumnStyles
            .Add(l_aCol1)
            .Add(l_aCol2)
            .Add(l_aCol4)
        End With
 
        If Not DataGrid1.TableStyles.Count > 0 Then
            DataGrid1.TableStyles.Add(l_dgts)
        End If