Domain redirection

Please excuse the possibly idiot question, but it's 4am and my brain is fried from wrangling with unhelpful tech support at another company.

Here's my situation:
* I have a new domain+hosting package with dreamhost (domain A)
* I have an old domain name that's not currently pointing at anything in particular (domain B)

I want to have domain B point to the site hosted at domain A (preferably redirected directly to the new URL as well, not just echoing the new content under the old URL).

I can change domain B's DNS record to point to DH's nameservers, but I know there's a step I'm missing: how do I set it up from within DH to display/redirect to the correct site?

I feel rather dense for not figuring this out, but it's very late and I'm now thoroughly tangled in all this. Help! :)

Many thanks,
Eleanor

When you add the domain to DreamHost using "Domains>Manage Domains>Add New Domain / Sub-Domain", you can specify the new domain as a redirected domain. Just specify the URL for your main site.