Have you created a blog and written a post yet?
If you have and it's not showing up, try regenerating the blogs by using this URL in your browser
http://www.yourserver.com/tools/cron/gen_blogs_full.php It will produce a blank page as it's only doing a regeneration but any new blogs or posts trapped in the cache will be released.
After regenerating the blogs, if the blogs still don't show up, check to make sure you have created the blog properly. You need to first create a Category for your blog, once you have created a category you can then post a topic and write your blog by clicking the "New Post" link next to the category.
If regenerating the blogs does work, you need to check to make sure your crons are working properly. Search the forums, there's plenty of threads and posts about cron issues.