Do not understand SimpleFOAM algorithm in OpenFOAM
 

(1)Guess the pressure field p*
Solve the momentum equations to obtain u*,v*,w*
Solve the p' equation (continuity)
Correct pressure field p =p*+p'
Calculate the velocity corrections
Correct velocity field
Treat the corrected pressure pas a new guess p* and go to

I do not know how we can find p' from continuity?

Mr. Peric is your friend. He wrote full book explaining exactly what you asked.

I cannot find his book.Can you give me ebook or a link?

read the book by Versteeg and Malalasekera.

The code follows the dissertation of Jasak. Check his dissertation and walk through the code with his equations and explanations.