You can't. (This is to prevent people from using this method as a way of submitting a link, but with their comments in a privileged position at the top of the page. If you want to submit a link with comments, just submit it, then add a regular comment.)"
Comments
From the FAQ (http://ycombinator.com/newsfaq.html):
"How do I make a link in a question?
You can't. (This is to prevent people from using this method as a way of submitting a link, but with their comments in a privileged position at the top of the page. If you want to submit a link with comments, just submit it, then add a regular comment.)"
Emphasis mine.