How to setup user in Ubuntu 8.04 Desktop Version??

Hello everyone,I'm really new on Linux & Ubuntu also, anyone can teach me to setup the system? My system is using Dell PowerEdge T105 as a File Server & i really don know how to change the Workgroup, cause i follow others people give the step, i found the smb.conf file, but after i change the Workgroup, it cannot be Save.I also not familiar in the command key. When i see all the command key, i really feel complicated....Thank you.