They did not do anything. It was part of their belief.
The afterlife was a main concern of the Egyptian civilization.
The tombs of the ancient Egyptian pharaohs and nobility are filled with items that would be needed in the Egyptian afterlife. Also the uncovered writings of the ancient Egyptians speak about the afterlife.
The ancient Egyptian belived in afterlife. And that was why the mummified the dead in preparation for this.
The afterlife
Mummification
Heaven.
The book of the dead.
=== === === === === ===for more information about why the heart was left in the body type in this question What were the steps of Egyptian afterlife?
Embalming
the answer is 50 to 100 thousand years
Pharohs and their belongings to help them trough the afterlife
Osiris was the ancient Egyptian god of the afterlife. Husband and sister of Isis.