how to change color of "ls" command

use "man dir_colors" for detailed help.
copy "/etc/DIR_COLORS" to "~/.dir_colors" to create user-defined color file.

to ease visibility of folder color with blackground, change default setting
 on line 59:
"DIR 01;34     # directory"  #i.e. darkblue
to
"DIR 04;36     # directory"  #i.e. darkcyan, underline

This is enough.