How are yesterday's missed Maghrib and Isha prayers to be made up along with today's new prayers?

Delaying prayer beyond its prescribed time out of complacency and laziness is a great evil that necessitates repentance. The one who does so is warned by Allah Almighty's saying: "So woe to those who pray, [but] who are heedless of their prayers." (Al-Ma'un: 4-5). Missed prayers that were not due to a valid excuse must be made up immediately, in their proper order, unless the time for the current prayer is pressing, in which case it should be performed first.