How do I perform salat al Tawba?

It is reported for Sunday of Dhul Qa’dah- 4 units with Fatiha, 3 ikhlas and once each of Falaq and Naas, followed by 70 astaghfar and la hawla wa la quwwata ila billah.
Then after the prayer recite:

يا عَزِيزُ يا غَفَّارُ، اغْفِرْ لِي ذُنُوبِي وذُنُوبَ جَمِيعِ الْمُؤْمِنِينَ والْمُؤْمِناتِ فَإِنَّهُ لا يَغْفِرُ الذُّنُوبَ الَّا انْتَ

It is mustahab, so you can pray it any time with intention of rajaa al-matlubi