Guru Nanak Dev Ji was the Founder of Sikhism. He was the first Sikh Guru. Here you can read Guru Nanak's Biography based on Janam Sakhis. Janam Sakhis are The Life History of Guru Nanak Dev Ji in other words we can say it 'Guru Nanak Dev Ji di Jivani in Punjabi'. You can read here Teachings of Guru Nanak dev ji based on Guru Granth Sahib or Adi Granth and great Sikh History.