At this point we should mention C-x u which is the undo option it
will undo the last act. You can do several of these in a row,
notice there is a big difference between C-x u and C-x C-u
you must let go of the Ctrl key, before hitting the u key.
Handeling files and buffers can be done with menus on top but also
with shortcuts: opening a file is with C-x C-f you can use the tab to
complete file names as you can in the bash/tcsh command prompt.
When executing emacs from the command line you can give it a file name as
a parameter, in both cases emacs will create a new file should the file not
exist.
Saving is done by C-x C-s which saves the current buffer(file) or
C-x s which will prompt to verify and save each and every open buffer.