There is only one Allah i.e. one God. The prophets were the messengers of Allah and Muhammad was the final prophet. It is the ultimate word of Allah. The angels serve and praise Allah. There are four Archangels including Gabriel the highest angelic being.
Angels record the good and bad deeds of humans.
There will be a day of final judgment when all humans are resurrected and become accountable for their deeds. What we experience in the afterlife will reflect how we have lived in this world and whether or not we have had faith in and been obedient to Allah. For those who have lived justly and mercifully the afterlife will be a garden Paradise. For those who have not it will be a tortuous hell. There are five basic duties of a Muslim also called the Five Pillars of Islam.