I am trying to configure a fresh installation of FreeBSD using VMware workstation. I get to a screen where I have to configure the Network Interfaces (some values are set automatically because I've selected DHCP Auto in options) but the hostname is empty and domainname is .localdomain. What values should I write in there?
You should give the computer a name; if you don't have a DNS server on your network it doesn't really matter what you name it. If you're on a network with a DNS server, consult your DNS admin for what it should be named.
For example, you might name the computer "Beastie", and keep the domain name "localdomain".
Also, if you haven't found the FreeBSD Handbook yet, it's full of good information and walkthroughs. More advanced configurations can be found on the FreeBSD Diary too (though some articles are outdated).