HI I'm Jenn and this is my first time asking a question.
I don't know very much about computers ( my daughter is the wizz, and she installed linux for me) - and i love it

I just ( for the first time) installed something ...
How do I know it finished installing, and what do I do ( just close the window) ?

( it says : ( jenn@jenn - laptop $)
in green.

THANKS

Hi Jenn and welcome to LinuxQuestions! What you see:
is the command prompt, that is a string displayed inside a terminal and waiting for user's input. We cannot tell if your installation went successful only because it returned the command prompt. You have to see if you received some error message toward the end of the process.

At this point you can only test if you can execute the installed software. If you need some help, please provide some more details, e.g. what software did you installed? What are the commands you issued to install it? What is your Linux distribution?

What did you install and how?

Anyway, that is the prompt and it shows up once the previous command ended. If it was unsuccessful then you will probably see some error messages before it ended.

Also, each command returns an "exit code". It's usually 0 for success and some other number for failiure. The exit code of the previous command is stored in the variable "?", so you can check it like this:

(the dollar sign makes the shell treat the following word as a variable rather than literal text)

If you want to learn more about the command line, see the tutorials in my sig.