What's the problem? I don't usually use Xanga, so I really don't really know how to help you, but looking at the urls for links when I log in, this looks like the way to go to reach your friends' journals:

http://www.xanga.com/home.aspx?user=*insert username here, without asterisks*

So it'd be this for my Xanga:

http://www.xanga.com/home.aspx?user=thisvainvein

I hope that helps.