NOT A TEACHER
(1) As the other posters told you, the "'good" English is: How are things?
(2) But native speakers speak fast (in your language, too?), so it is OK to
say "How's things?" BUT it is not OK to say "How is things?"
(3) You can say:
There are 50 states.
There's 50 states.
BUT you cannot say "There is 50 states."
("There're 50 states" is correct but too difficult to pronounce.)
(4) Please remember that "How's things?" and "There's 50 states" are OK in
informal English. Do not use them in formal English, such as reports that you write
in school.