What you explain is very much the same as the linked demo. In the demo I linked, a RadWindow is opened. After that a value is taken from textboxes (which is basically the same as a concept as taking a grid value) and then when the Update button is clicked, the value is sent to the main page.
When you install RadControls, our online examples projects are automatically installed on your computer and you can not only examine their full source code, but also extend them further in order to meet your requirements.
You can open the demos from here:
Start\Programs\Telerik\RadControls for ASPNET AJAX\Open Sample WebSite In VisualStudio
The actual location on your hard disk is the following one:
C:\Program Files\Telerik\RadControls for ASPNET AJAX \Live Demos
Please, examine the logic of the demo in more details and replicate the concept for your case. In case you continue experiencing issues with that, make a fully runnable demo with what you have done so far along with detailed explanation of the exact issue, open a new support ticket and send it to us. Once we receive that we will do our best to help.
the Telerik team
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