Before you do anything you should shut down any services that you wont need and secure the server good, I've seen servers hacked within hours of being placed online. I'm not sure what OS you are using but here is a good Linux site for securing a machine.
http://en.tldp.org/LDP/solrhe/Securi...-Edition-v1.3/
Webmin couldnt be easier, but be careful with it, its a powerful tool. It runs as root and you could mess shit up if you don't watch what you're doing.
Hopefully when they did the server install they included Apache, Sendmail (if thats what you are going to use), Bind, etc. If so then its just a matter of configuring which is a piece of cake using Webmin. If not you have the fun task of installing them.
Have fun and if you need help with anything just post it on here
