If you need to open a new browser window or tab to an external website from a C# Code Snippet in Infor CRM (Saleslogix) Web, which is server-side code, you can easily create Javascript and add it to the page so it executes when the post back that fired the C# Snippet completes.
In the C# Snippet, add code like the following:
var script = "var win = window.open('http://google.com');";
ScriptManager.RegisterClientScriptBlock(this, GetType(), "OpenExternalWebsite", script, true);
This registers the javascript to open google.com in a new browser window/tab on the page. Now when the postback completes, the javascript will run and open the website. This sort of thing can especially come in handy when you need to do some server-side code and conditionally open the website based on some conditions.