http://www.webconfs.com/how-to-redirect-a-webpage.php
Depends on the technology you use. If you retain the hosting accounts for the domains you are redirecting then you can use a simple PHP redirect. If they are hosted on an apache server you can use mod rewrite or an IIS server you can use ISAPI to do the same thing.
Some domain name registrars will allow you to park a domain for free and 301 redirect but be warned - this isn't the same as "forwarding" the domain, which will end up with the same problem you have just now.
Speak to your host and emphasis you want a 301 redirect (not 302, no forwarding, etc).
Scott