comp name

[Argus]

ok, i'm new to linux, so this may be one of the first things you guys learned 
and may seem stupid, but...
i don't know any of the vocabulary, so i don't know where to look this up.
how do i change the computer name in the normal prompt?
for example
[root@something /root]#
how do i change the 'something' part to a name i like?
thanx, for all your patience...
Argus