Non-trivial Editor Keys:

ENTER           Execute input when it is a complete lisp expression,
                otherwise add a LF to the command string and continue editing.
CTRL+ENTER      Add a LF to the command string and continue editing.
TAB             Show completion list for the symbol before the cursor.
                Press TAB,SHIFT+TAB to navigate in the completion list.
                Press ESCAPE to cancel.
                Press ENTER to accept the current choice.
                Press any other key to accept the current choice and that key.
ESC             Cancel input or code completion.
UP              Move up in history.
DOWN            Move down in history.
CTRL+C          Copy the selection to the clipboard.
CTRL+V          Paste source code from the clipboard into the REPL.
CTRL+W          Delete word before the cursor.
CTRL+U          Erase to the begin of the line.
CTRL+K          Erase to the end of the line.

Your terminal program provides scrolling through the scrollbars.