adding external links to pages

I swear, I did this before, but now cannot remember how I did it. I am using a child theme bases off of twentyten. I am adding new pages with a title, which become links in my menu. The only choice is to be within my blog though (https://www.mysite.com/blog) and I am seeking to add an external link outside of that capacity. (www.anothersite.com), but keep it as a menu link.