What operating system will/is this server running?
If its Linux the best advice i can give you is to find the distro (usualy redhat) and install it on a old computer to "play" with this will help you gain the best understanding on how the OS works.
You will also need a SSH client to access your server you may want to look at putty
http://www.chiark.greenend.org.uk/~sgtatham/putty/ (windows OS) or if you are using Linux at home just type SSH
www.domainname.com and you will connect to the server.
One of the most important things you will need to learn is Shell comands for example:
CD /home/stewis/www : changes the current browsing directory to /home/stewis/www
top : displays current running processes as well as some details about your server.
vi filename.txt : starts vi or vim as your text editor and opens filename.txt (i usualy use pico but vi/vim seems to be on most servers)
dir : gives you a directory listing
there are lots more shell comands you may want to look around the net for them as well as looking in a localbookshop for books about Linux.
If the server is windows based i think you can use remote desktop but i am not sure because i have always used Linux.
And remember if you have a server control panel installed on your server it usualy can do most things but theres always something you will have todo your self so its best to learn early.
a good place to look for help is ev1servers support forums theres loads of howtos and information on how to run and secure your servers.
http://forums.ev1servers.net
Stewart McIntosh