Complex sentence: He said all of you should recite the Du'a of Prophet Khidr, this du'a recite ether on the 15th of Shaban (Islamic month) or on a thursday night or when ever you can.
Split into simpler sentences: He said all of you should recite the Du'a of Prophet Khidr. This du'a should be recited either on the 15th of Shaban (Islamic month), or on a Thursday night, or whenever you can.