Yes you can get the DNS details from the manage domain page by clicking on the DNS link next to your sub-domain. Sometimes it takes a while to appear so just keep checking it if it has not shown up yet.
You will then need to wait 0-72 hours for the DNS zone to propagate around the net before you can view your new site at DreamHost. However you can mirror it to a *.dreamhosters.com site so you can start working on the site.
See the wiki page here for details.
Opinions are my own views, not DreamHosts'.
I am NOT a DreamHost employee OK! :@
Act on my advice at your own risk!