[plug] forwarding email

[sol]

Hello PLUG,

I'm quite unfamiliar with email servers, but I've got one running with a bunch 
of email addresses that is working fine. But I can't work out how to get 
email to automatically forward to another email address. 
ie: so that all mail sent to sol at domain.org gets forwarded to 
sol at autonomon.net
I thought this was just a simple case of editing an alias file or something, 
but which one?
I'm using uw-imapd on Debian Woody.

Thanks,
sol