You have to cut and paste your blog posts from your outside blog into your profile page here on the network to get them to appear on our main page. Go to your profile page and scroll down and look for the link that says "add a blog post." You can paste in your latest post from your outside blog and it will show up on the main page of the network until it gets bumped down by newer posts from other people. This is a great question, I need to put it into the FAQ, thanks!