emacs 4: Offical Tutorial Part 2

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Use Meta + g, Meta + g to bring up the Goto line: mode at the bottom, then enter the line number that you want to jump to and enter, the editor will take you to that line.

Use C-/ to undo things because this is the most convenient way of typing,   much easier than C-/_ and C-x u ( three keys).

One special thing about the command for finding a file is that you
have to say what file name you want.  We say the command "reads an
argument" (in this case, the argument is the name of the file).  After
you type the command

        C-x C-f   Find a file

Emacs asks you to type the file name.  The file name you type appears
on the bottom line of the screen.  The bottom line is called the
minibuffer when it is used for this sort of input.  You can use
ordinary Emacs editing commands to edit the file name.

While you are entering the file name (or any minibuffer input),
you can cancel the command with C-g.

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