I was wondering how can I perform my Qaza salat. I mean how many rakat salat do I have to pray for Fajr, Zuhr, Asr, Magrib and Isha. And what time do i have to perform it?
With the intention to make up whichever salat you've missed, pray the qaza as soon as you can. There are some times when it's makrooh to offer salat (sunrise, sunset), other than that as AlSayed Ali mentioned, the sooner the better.
Note: Makruh is not haram, but it is better not to do ...
The performance of them relatively is the same in the number of the Rek'ats and likewise in the circumstances. But you ought to change the intention (Niyyah) of them from Wajib to Qaza.
In regard to their time, I should mention that it is not Wajib that you definitely do them in their specified time. But perhaps it could be better if you do them on their specified time (or even it could be better you do them as soon as you can).
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