Assalamu alaikum wa rahmatullahi wa barakatuhu!
In the Name of Allah, Most Gracious, Most Merciful
The Prophet Muhammad (saw) taught this namaaz (Salaat-ul-Tasbeeh) to his uncle Hazrat Abbas (ra).
He (saw) told his uncle that by performing this prayer, all past, present, old, new, small and big sins would be forgiven, inshallah.
Prophet Muhammad (saw) also stressed that this namaaz can be prayed everyday, once a week, once a month, once a year or even at least once in a lifetime.
Method: Firstly, make the niyyah (intention) that I am praying 4 rakaats Salaat-ul-Tasbeeh for the sake of Allah and I am facing towards the Holy Kabah, then say Allah-u-Akbar.
Then, men fold their hands on the navel whilst women fold their hands on their chest, and then say the prayers as per the following chart with this tasbeeh which will be recited 75 times in every rakaat.
For more information about Salaat-ul-Tasbeeh, click here.