SIlverlight Application and windows notification with RIA services

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C#

Windows

XAML

Silverlight4

RIA

, +

Hello ,
I am working on project with Silverlight 4 and Local Web hosting and i am really new to web Development.
What needs to be done is here :
Host a Website with Sign-In / Sign-up Page (DONE . Business Application does work)
Able to see settings page which holds textboxes and labels and Update Button (Design Done)

Host website on Local Lan server Using IIS (Done)
Now what i need to know is :
when client updates settings using other computer on LAN the main computer (host server ) should get notification that settings has been changed and should be able to receive a new settings file from client computer.

so i am sure we need WCF RIA services to hold a data from textbox.
the more easy way to understand this is : Let's say you have a registration form for some event then host that website on local server Only where people can come and register for event then you should be able to see if anyone registered (by windows message ) and you should be able to see registered forms.

Thanks and Regards,
Mohit.