How to inplace edit in telerik grid writen in update code

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VB

ASP.NET

<Telerik:RadGrid ID="GVSales" EditMode="InPlace" AllowMultiRowSelection="True" runat="server" AllowFilteringByColumn="true"
ShowFooter="true" GridLines="None" CellSpacing="1" CssClass="RadGrid_Metro" Skin="Metro"
AllowPaging="true" PageSize="1000" AllowSorting="true">
<clientsettings enablerowhoverstyle="true">
<Selecting AllowRowSelect="false" />

<groupingsettings casesensitive="false">
<exportsettings filename="esireport" ignorepaging="true" exportonlydata="true" openinnewwindow="true">

<mastertableview autogeneratecolumns="false" editmode="InPlace" summary="RadGrid table" width="100%">
CommandItemDisplay="Top">
<commanditemsettings showaddnewrecordbutton="false" showrefreshbutton="false" showexporttoexcelbutton="true">
<columns> <telerik:grideditcommandcolumn xmlns:telerik="#unknown">
<telerik:gridboundcolumn datafield="salesreg_gid" headertext="Sales ID" visible="false" xmlns:telerik="#unknown">
ItemStyle-HorizontalAlign="Center">

<telerik:gridtemplatecolumn headertext="Booking Refno" itemstyle-horizontalalign="Left" xmlns:telerik="#unknown">
ItemStyle-VerticalAlign="Middle">
<itemtemplate>
<asp:LinkButton ID="btnEdit" runat="server" CssClass="GSTA_hyperlink" Text='<%# DataBinder.Eval(Container.DataItem, "salesreg_bookingrefno") %>'
CommandName="btnEdit" ToolTip="Click to View & Edit" CausesValidation="false"
CommandArgument='<%# DataBinder.Eval(Container.DataItem, "salesreg_gid") %>'>


<telerik:gridboundcolumn datafield="salesreg_bookingdate" headertext="Booking Date" xmlns:telerik="#unknown">
ItemStyle-HorizontalAlign="Left">

<telerik:gridboundcolumn datafield="custgroup_name" headertext="Customer Name" itemstyle-horizontalalign="Left" xmlns:telerik="#unknown">

<telerik:gridboundcolumn datafield="custgroup_description" headertext="Customer Location" xmlns:telerik="#unknown">
ItemStyle-HorizontalAlign="Left">

<telerik:gridboundcolumn datafield="product_name" headertext="Product Name" itemstyle-horizontalalign="Left" xmlns:telerik="#unknown">

<telerik:gridboundcolumn datafield="salesreg_noofunit" headertext="Quantity" itemstyle-horizontalalign="Left" xmlns:telerik="#unknown">

<telerik:gridboundcolumn datafield="salesreg_invoiceno" headertext="Invoice No." xmlns:telerik="#unknown">
ItemStyle-HorizontalAlign="Left">

<telerik:gridboundcolumn datafield="salesreg_invoicedate" headertext="Invoice Date" xmlns:telerik="#unknown">
ItemStyle-HorizontalAlign="Left">

<telerik:gridtemplatecolumn headertext="Action" itemstyle-horizontalalign="Center" xmlns:telerik="#unknown">
ItemStyle-VerticalAlign="Middle">
<itemtemplate>

<asp:ImageButton ID="ImageButton1" CausesValidation="false" runat="server" ImageUrl="~/images/Button_Delete.png"
ToolTip="Click to Delete" OnClientClick="javascript:return confirmDelete();"
CommandName="Delete" Height="25px" Width="25px" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "salesreg_gid") %>'>



<pagerstyle horizontalalign="Right">




Private Sub RadGrid1_ItemCreated(ByVal sender As Object, ByVal e As Telerik.Web.UI.GridItemEventArgs) Handles RadGrid1.ItemCreated
If (TypeOf e.Item Is GridDataInsertItem AndAlso e.Item.IsInEditMode) Then
'init insert operation triggered
ElseIf (TypeOf e.Item Is GridEditableItem AndAlso e.Item.IsInEditMode) Then
'edit operation triggered
End If
End Sub

What I have tried:

how to write code for update can any 1 help me