See... the thing is that your blog is hosted on a free server from wordpress. To move your existing blog over to dreamhost, you would need access to the database to be able to make a back-up. Ask the wordpress support if they can make a back up of your site. If not, you're out of luck and you'll have to do things the really hard way (copying and pasting your entries into a new wordpress installation).
That was the issue I had when I first had free blog hosting. When I moved to a new host, they wanted to charge a ridiculous amount for the back-up, but luckily I only had a dozen or so entries.
anyway, if you can get a backup of your site, you need to create a MySQL database on your dreamhost account. Just go to your panel and click on goodies, then go to manage mysql and create a hostname and then a database. Next you'd have export (transfer) the data from your backup into the new database, while modifying some things like the new database name, its new host, and username/password. after that, you upload everything to your new site through an FTP program.
That's a really generalized version, and I'd be glad to go indepth, but you should ask first whether you can get a backup of your site or not.
You can look at the links below for support as well.