I created a new folder on the terminal and is not shown in the finder
One of the most probable cause for this to happen is that you inadvertently entered a name which the Finder isn't able to display correctly (or doesn't display to protect us from the complexity of the underlying Unix filesystem).

To check this hypothesis, please from iTerm go into the parent directory of the one you created let's say its name is foo bar and enter:

ls -aBdl 'foo bar'


The -B option will display any non printable character as a \xxx where xxx is the octal value of the non printable character.
This option is very helpful to deal with filenames which cause problems to shells and graphical interfaces like the Finder.