Please tell me about the correct way of doing sujud as sehu

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Sujud as-Sahu consists of two Sajda (two prostrations). One can do them before or after uttering salam at the end of prayer. It is reported in Sahih Muslim from Abu Sa'id al-Khudri (RAA) that the Prophet (Sallallahu Alaihi wa Sallam) said: "When any one of you is in doubt about his prayer and he does not know how much he has prayed, three or four Rak'ahs, he should cast aside doubt and base his prayer on what he is sure of, then perform two prostration before giving salutation." [ Bukhari ]
Another narration concerning story of Zul Yadain that the Prophet (Sallallahu Alaihi wa Sallam) performed the two prostrations after giving salutation.
So, the best way is to perform the two prostrations just as done by the Prophet Mohammad (Sallallahu Alaihi wa Sallam), i.e. where he made the prostrations before giving salam, we should do the same and where he did so after giving salam, we should do the same. Then, one can choose to make the prostrations before or after giving salam in case of nothing is reported from the Prophet (Sallallahu Alaihi wa Sallam).
It is reported in Sahih Muslim from Ibn Mas'ud that the Prophet (Sallallahu Alaihi wa Sallam) said: "If one increases (i.e. some actions in prayer) or decreases, One has to perform two prostrations"
Here, we add that a worshipper has to perform these two prostrations just as he normally makes prostration, i.e. with supplication, tranquility and remembrance of Allah.
Then, if these two prostrations are done after giving salutation, one has to utter salutation instantly after performing the prostration without Tashahud. This is the dominant opinion among scholars.
Allah knows best.