Who
      was the first khaleefah and what is the story of Ghadeer Khum?
Question

                cause i am bit confused regarding this matter so what does shia's believe that hazrat "ali" is a first caliphate and we sunnis say that hazrat"abbubakar " is the first caliphate.so u better tell who is the first caliphate and what is the that will which prophet "mohammed"(peace be upon him) want to give to his kinsmen and what is the event take place at ghadeer .
Praise be to Allah.The
      first khaleefah who succeeded the Messenger of Allaah 
 (peace and
      blessings of Allaah be upon him) was Abu Bakr al-Siddeeq (may Allaah be
      pleased with him), according to the consensus of the respected scholars,
      because of the consensus of the Sahaabah who all gave their bay’ah
      (allegiance) to him. This was after an initial dispute between the
      Muhaajireen and Ansaar, then the Ansaar were convinced and gave their
      bay’ah to Abu Bakr, and they did not differ amongst themselves, and they
      did not hesitate in making a choice between Abu Bakr and ‘Ali (may
      Allaah be pleased with them both). None of the Sahaabah asked to give
      bay’ah to ‘Ali after Abu Bakr and before ‘Umar (may Allaah be
      pleased with him), and no one asked to give bay’ah to ‘Ali after
      ‘Umar – may Allaah be pleased with them all. The fitnah and
      differences arose because of the murder of ‘Uthmaan (may Allaah be
      pleased with him). The Sahaabah (may Allaah be pleased with them) accepted
      for their worldly affairs the one whom the Messenger of Allaah had
      accepted for their religious affairs, the one who had acted as the deputy
      of the Messenger of Allaah 
 (peace and blessings of Allaah be upon
      him) in leading the prayers [when he was unable to do so – i.e., Abu
      Bakr].
With
      regard to what happened at Ghadeer: Ghadeer is the name of a well in a
      place between Makkah and Madeenah which is called Khum. The hadeeth was
      narrated by Imaam Muslim in his Saheeh
      (no. 2408) from Zayd ibn Arqam, who said: “The Messenger of Allaah 
      (peace and blessings of Allaah be upon him) stood up and addressed us one
      day at a well called Khum, between Makkah and Madeenah. He praised Allaah
      and exhorted and reminded us. Then he said: ‘I am leaving among you two
      important things: the first of which is the Book of Allaah’ – and he
      urged us to adhere to the Book of Allaah, then he said: ‘And the people
      of my household (ahl bayti).
      I remind you of Allaah with regard to the people of my household, I remind
      you of Allaah with regard to the people of my household, I remind you of
      Allaah with regard to the people of my household.’” Zayd said: his
      wives are among the people of his household, but the people of his
      household who are forbidden to receive sadaqah (charity) after his death
      are the family of ‘Ali, the family of ‘Aqeel, the family of Ja’far
      and the family of ‘Abbaas. All of these are forbidden to receive
      sadaqah.” [abbreviated version].
      
      
      His advice concerning the people of his household has to do with honouring
      and respecting them, and not exposing them to abuse or annoyance. This
      does not mean that they are to be given preference over others who are
      known through the texts to be more virtuous than them, such as Abu Bakr,
      ‘Umar and ‘Uthmaan (may Allaah be pleased with them all).