Window popup

[rAs1234]

Hello.
I need to use a popup window. In the popup window will have two buttons.
After pressing need to hide the popup window using C # and store the value.

[Shinu]

Hello,

One option is using the RegisterStartupScript() server method to invoke the client method to close the window. More information on invoking the client function will be available in the KB Article.
Executing JavaScript function from server-side code

The following forum  also discussed similar scenario.
closing rad window

And for your second requirement, storing the values, you can attach OnClientClose  event and handles the values.
Please checkout this documentation
Using RadWindow as a Dialog

Thanks,
Shinu.