It's fairly straight forward. I helped a friend with this last night.
Upload your wordpress site to your online space.
You'll need to export your local database and import it to your online database. Update your wp-config.php file with the online database credentials. Then there is a few queries you need to run on your database info in order to sanitize it for your new domain. See http://www.mydigitallife.info/2007/10/01/how-to-move-wordpress-blog-to-new-domain-or-location/ for the queries. Once those queries are run you should be good to go.
Let me know how it goes.