Basic screen usage

screen	Simply start a screen session
screen -ls	List current screens
screen -dr sname	Re-attach to the sname screen
screen -xr sname	Re-attach to sname in multi-user mode

Once within screen, the control sequence is ^a (ctrl-a), for example:

^a ?	Display help information
^a c	Create a new screen
^a 0	Change to screen 0
^a 2	Change to screen 2
^a d	Detach