I'm trying to use Emacs and everything is fine, but the information about every file in my directory is too comprehensive. How can I tell it to show only file name (and maybe filesize in human readable format)? I tried options like dired-listing-switches but without any luck.
You can reduce the amount of information displayed by using Emacs' ls emulation instead of allowing it to use ls directly.
To enable ls emulation, add the following code to your startup file (probably .emacs or .emacs.d/init.el):
(require 'ls-lisp)
(setq ls-lisp-use-insert-directory-program nil)
You can then customise the display with M-x customize-group RET ls-lisp RET. Specifically, the "Ls Lisp Verbosity" setting can be used to disable a number of columns. There's no obvious way to get it down to just the filename and size, but you can certainly get rid of the owner/group/link-count columns.