使用现有.NET页面更新另一页面的一部分的最佳方法

I'm working on an ASP.NET WebForms CMS application, and having a bit of trouble solving a particular problem. For a while now, I've had a menu on the side of the admin console that shows a list of the pages, links, etc that make up the sitemap. Users could click on an entry, bringing up a flyout menu at the point of the mouse click. This menu has options like update page, view page, delete page, etc.I'm working on an ASP.NET WebForms CMS applicat