How does one pray for one's parents after their death?

The meaning of "Salah" (prayer) in the Hadith is supplication for forgiveness, mercy, entry into Paradise, and deliverance from Hellfire, as in the Almighty's saying: (Take, [O, Muhammad], from their wealth a charity by which you purify them and cause them to increase, and invoke [Allah's blessings] upon them. Indeed, your invocations are reassurance for them). Here, "invoke [Allah's blessings] upon them" means supplicate to Allah for them, and "your invocations" means your supplications.