screen is simply a command that gives several virtual terminal from one ssh session and they don't expire with ssh
after you start your ssh session just type screen and start working and if the connection is diconected when you log back in just type screen -ls to list the screen sessions available, output as follows
There is a screen on: 10244.pts-0.ramezhanna (Attached)then you type
and READ THE DAMN MAN PAGES :)
Cheers..
