Passing the current url to Excel

Hi, I need to pass the current url in the website to Excel.
Case is
Step 1: I got a button in a ASP page, click a button to close the window and grab the current url
Step 2: create a variable in Excel-addin projct (C#, .net4, vs 2010) which is used to save this url.
Step 3: Pass this url from asp web page to c# Project.
 
Can anyone help me please?? Thx!!!!!!!!!!!!!!
 
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