Basics of using screen:

Start: screen
Deattach: Ctrl-a + d within screen session
Reattach existing session: screen -r [session-name]
List sessions: screen -ls

Commands: Ctrl-a and additional key:

• d – detach session
• n, p – move to next, previous screen session
• c – create new window
• " – list all windows
• Ctrl-a – switch to other screen
• Shift-a – rename window (shows better in window list)

Links: LinuxJournal article