Please refer to your receipt for the user name and the license key. 

 

For web applications:

Since the Log class is a static class a good place to set the UserName and LicenseKey is in the global.asax application start

 

For web services, WCF, WinForms, Console, and WPF applications:

Set the UserName and License Key when your application starts.

 

Log.UserName = "User Name From Receipt";
Log.LicenseKey = "LicenseKey From Receipt";