Toilet is translated as 厕所 in Chinese. It is pronounced as 'cè suǒ'.
Public toilet is 公共厕所 - gōng gòng cè suǒ
公共 (gōng gòng) means public.

If you want to ask a direction of a place, you can start the sentence with ' xxx 在哪里?' -- zài nǎ lǐ , meaning 'where is xxx?'

When asking direction for toilet, you can say '厕所在哪里?' -- cè suǒ zài nǎ lǐ
Or you can be polite by adding '请问' - qǐng wèn, meaning 'can you please tell me'

Female toilet often has 女 (nǚ) written on the door, meaning female.
Male toilet often has 男 (nán ) written on the door, meaning male.
Its important to remember that to avoid going to the wrong one.