Extracting a hyperlink from the command line

I'm new to c# and need a bit of guidance on something that I fear is very obvious (but haven't figured out).  I want to pass a hyperlink via the command line to a variable called strHyperlink.  I was thinking of something like this for the command line:

D:\Testbed\Sandbox.exe http://website.com

I have added the variable to the Form class

string strHyperlink = Environment.CommandLine;

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However, when I try to view the switch using the following:

var result = MessageBox.Show(strHyperlink, "Test", MessageBoxButtons.OK, MessageBoxIcon.Information);

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I get:

"D:\Testbed\Sandbox.exe http://website.com"

Can someone please let me know how to get the hyperlink (in the cleanest possible way).  Thank you.