Pages appearing twice on navigation bar

I noticed on this page you can input a code to exclude a page from the navigation bar on the top. I have static pages in use and if you go to http://www.twillingatenl.com you will see that Welcome to Twillingate; the page I’m using as the site homepage is there as Home and as Welcome to Twillingate. I want to exclude that page from the navigation so it just says home.

How can I input that code? Where do I input that code?

My problem is similar to the problem of the person that made this thread:

http://wordpress.org/support/topic/109630?replies=8#post-529950

I just can’t find that code in my header.php either.