I suspect "xterm" isn't what you want to learn, you want to learn the Linux command line.

Also known as "OK, I tapped the xterm icon, now what?"

Like most things, the best way to learn is to have a reason to, a job you want to do. I figure most of the things you want to do will be:
- understand some terms like "directory" and "device"
- see what is in each directory
- move between directories and know how to get back where you came from
- look inside files
- move files, copy files, rename files
- have some idea of the layout so you know where to find things
- know about some tools that give you more than the file manager does.

Basically, what you want is a simple Linux/unix tutorial.

Any of the basic linux tutorials will give you all that. many will have things you don't really need to know at the moment, like how to create users, or the boot process.

try http://www.linux-tutorial.info/ and look at the first three sections in the basic tutorial. The rest will be good for you, but not required

If you find that doesn't really work for you, then look for other "basic linux" or "linux tutorial" sites.

Some things to learn to do (to give you a reason to mess about)
- learn what the name of the directory is that you get dropped into when you start xterm. How can you tell when you are there?
- learn about the ls command and what is different if you use ls compared to ls -a. And what is different when you use ls -aR. Why might you do that?
- learn how to navigate to the /etc directory
- learn how to see the contents of /etc/mce/mce.ini
- learn how to find what processes are running on the system
- learn how to create a directory to put files in
- learn how to put files there.

Zebee