Its description:

It consists of two Rak‘ahs like the Fajr Prayer. It is recommended that Imam recites the Soorah of Al-Jumu‘ah (Chapter 62) after reciting Al-Faatihah, and in the second Rak‘ah he may recite the Soorah of Al-Munaafiqoon (Chapter 63) after reciting Al-Faatihah. He may also recite the Soorah of Al-A‘la (Chapter 87) in the first Rak‘ah and the Soorah of Al-Ghaashiyah (Chapter 88) in the second Rak‘ah. There is no harm if he recites something other than that.

Whoever catches up a Rak‘ah with the imam, he should complete his prayer (after the imam says the Tasleem) as Jumu‘ah prayer.

But if one catches up with the imam after he has stood up from bowing in the second Rak‘ah, this means that one has missed Jumu’ah prayer, and has not caught up with it. In this case one has to stand up after the Imam has said Tasleem and complete his prayer as Thuhr with four Rak’ahs.