Linux, by default lists directories by ls at a format that it's impossible to recognize which object in the list is a directory, which one is an executable , which one is a link. You can use some utilities to make it understandable but the easiest way to do is editing a simple file in your home directory.To do this follow these simple steps...

• cd to your home directory by simply typing cd
• Edit your rc file if you don't what it is it's probably .bashrc. You can use an editor of your choice. If you use vi type "vi .bashrc". Other possible editors are emacs, jed, joe...
• Type i to go into the insert mode in the vi editor. Type "alias ls='ls -F --color"
• Hit the ESC key to enter to the command mode. Type : wq and it's done.
• Logout with exit and login again.