Why do the Shi'as believe that their Imams can provide divine guidance?

We all know for sure that Prophet Muhammad Sallahu alayhi wassalam was the last Prophet and the seal of the Messengers and he received the final revelation or the "Divine Message". I and most Sunnis believe that the Guidance is only from Allah and following the message of His Messenger (Sallahu alayhi wassalam) and infallibility in religion belongs only to the Prophet. However, I heard that the Shi'ah believe that the Imams also can guide people and are infallible. Is there any Qur'anic ayah or Hadiths that prove the same? Correct me if my understanding of the concept is wrong.