Maybe I can provide a more helpful answer.
First, you have to understand that UNIX does not have a graphical interface. The command prompt is all there is. The GUI is just another program, like bash or links, that is completely seperate from the OS.
With that in mind, one of the most common ways of accessing UNIX systems remotely is SSH. It's like telnet, but more robust, and more secure. When you install Linux, make sure to install SSH if it gives you an option. If it doesn't, you can assume it will do it. When you boot the system, the SSH server (sshd) will start automatically. From another UNIX system, or from windows clients using PuTTY (check google for it), you can log into it and control it as if you were sitting at it. On an UNIX system, open up a command prompt and enter this command:
ssh username@ip.of.Linux.box
Replace username with your username on the Linux box, and ip.of.Linux.box with the IP of the Linux box. You will be asked for your password, and then you will get a command prompt. That's all there is to it.
If you want a GUI, you have two choices: VNC or remote X. VNC requires you to set up the VNC server on your Linux box, and have the VNC client on your clients. Remore X requires each client to have an X server. Both of these are beyond the scope of this post, maybe I'll write a FAQ about it.