How to add child node for selected tree view node

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SQL-Server-2008R2

MVC4

am binding tree view from database ,and i have a button add node in my page

when i select a node in tree view then i click add node button am showing a popup with name text box.when i click add button i want to add child node for selected node in tree view

i want to insert selected node id as parent and name

What I have tried:

@helper GetTreeView(List<AccountsPageLayout.MasterNode> siteMenu, int parentID)
{
    foreach (var i in siteMenu.Where(a => a.ReportsTo.Equals(parentID)))
    {
        <li>
            @{var submenu = siteMenu.Where(a => a.ReportsTo.Equals(i.EmpID)).Count();}
            @if (submenu > 0)
            {
                <span class="collapse collapsible"> </span>
            }
            else
            {
                <span style="width:15px; display:inline-block"> </span>
            }
            <span id="category">
                <a href="#@i.EmpID" >@i.Name</a>

                @*<a href="@i.EmpID">@i.Name</a>*@
            </span>
            @if (submenu > 0)
            {
                <ul>
                    @Treeview.GetTreeView(siteMenu, i.EmpID)
                    @* Recursive  Call for Populate Sub items here*@
                </ul>
            }
        </li>
    }
}

adding node

<input type="text" name="MasterName">
               @Html.ActionLink("Add", "addMaster", "Treeview")

controller
public ActionResult addMaster(string ID)
{
return View();
}