How can I go any directory on a website homepage?

Question

Lets say I am on the forumxxx.com home page in webBrowser1. I want to go to forumxxx.com/register.php when I click button1 .
what code should I write in button1 click event? is there a code for that?

But I don't want to use webBrowser1.Navigate("forumxxx.com/register.php"); code in button1. because I am using an url list for my C# project. and This code should work on every sites. (not for forumxxx.com only)