when should you read qada namaz?

 Once a salat is rendered qadah, it must be offered (fardh only) at the earliest(except at forbidden timing), preferably before the next salat. In case of Fajr salat, it is not rendered qadah if it is missed due to reason beyond one's control (like, the alarm did not sound etc), so it be offered like a normal salat immediately on getting up(except at forbidden timing).

Salam

Fajr is Qada as the sun rises

Dhuhr gets Qada when it is time of Azan Al Asr

Asr gets Qada when its time for Maghrib

Maghrib Gets Qada as the sunlight completly goes

Isha Gets Qada at 12:00

As for Fajr you can perform as the sun rises, but that will be Qada.

As for Dhuhr, you cant perform after Asr but after Asr there are 2 Rakah`s that can be performed

Aisha (may Allah be pleased with her) said: Anytime Allah’s messenger (peace and blessings be upon him) came to my house after Asr he prayed two Rak’ah [Bukhari 593 ] The scholars’ analysis about these two Rak’ah turntoIslam.com

Imam At-Tahawee (may Allah have mercy on him) said, “Some people see no harm in praying two Rak’ah after Asr and consider them a Sunnah.” [Sharh Ma’anee Al-Athar 1-301] turntoIslam.com

Dhuhr can be performed i think 100% after Maghrib,not sure

if you perform Maghrib after the sunlight completly goes, then it'll be Qada