Tell me about Sunna after obligatory prayers?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Al-Sunan and Ar-Rawaatib supererogatory prayers are of two kinds.

1- Confirmed Sunnah. This kind includes: Four Rak'ahs before Thuhr and two after it, two Rak'ahs after Maghrib, two Rak'ahs after ‘Ishaa’ and two Rak'ahs before Fajr. The Prophet said: “Whoever performs twelve Rak'ahs every day and night, Allah will build for him a house in Paradise.” [At-Tirmithi]

2- Unconfirmed Sunnah: This kind includes four Rak'ahs before ‘Asr, two before Magrib and two Rak'ahs before ‘Ishaa'.

As for the night prayers, it is performed in sets of two Rak'ahs as recorded by Al-Bukhari and Muslim from ‘Aa’ishah .

At-Tirmithi reported that the Prophet used to perform eleven Rak'ahs between ‘Ishaa' and Fajr and he performed them in sets of two Rak'ahs, ending each set with Salam.

So, whoever adheres to the above-stated number, that is better; but if one increases or decreases, there is no harm.

For more benefit on supererogatory [Sunnah or Rawaatib] prayers, please refer to Fataawa 20804, 233800, 102385, and 88390.

Allah knows best.