I know Voldemort made 7 pieces of his soul and made 7 Horcruxes. Can anybody list down the order of making of all these Horcruxes and by the killing of whom, Voldemort made all these Horcruxes?
It is not explicitly said, but I believe I have the answer for you. Based on the order that was given to us in the books, the first Horcrux that Tom Riddle made, was his diary. The closest piece of him, potentially growing up in the orphanage and finding out he was a wizard. That of course, was destroyed by Harry Potter in the Chamber of Secrets.
The second Horcrux, I believe was the Ring of Marvelo gaunt. That one was destroyed by Albus Dumbledore. The third Horcrux made, would have to be the locket of Slytherin. That one, destroyed by Ronald Weasley. The 4th would have to be the Goblet of Helga Hufflepuff. Destroyed by Hermione Granger, in the Chamber of Secrets. The fifth Horcrux would be the diadem of Ravenclaw. Destroyed by Crabbe, in the room of requirement. The 6th Horcrux, Harry Potter himself. Destroyed by Voldemort, in the Forbidden Forest. The seventh Horcrux, of course, is Nagini. Destroyed by Neville Longbottom, in the final battle for Hogwarts.
The reason I believe it's this order is that because this is also the order that they were destroyed. Not only that, but these items, rank from most to least important to Tom Riddle himself. The diary, his only friend growing up. The ring is the last remaining piece of his family. The side of his family that he would never renounce. The lockets of his ancestor. As well as, the keepsake of the founder of his house. The rest of the houses, simply because of the founders of the school which he found important. He had intended to make the Sword of Godric Gryffindor, his final Horcrux. However, this was not something that he could do. Instead, he made Harry Potter, his long-lost cousin, heir to the invisibility cloak, is next Horcrux. Unintentionally. Finally, thinking that he had yet to make a 6th Horcrux, 1/7 fraction of his soul, binding his power in what he thinks is the most powerful magical way, he makes his closest follower, his second living Horcrux. One that would never leave his side.
The way that JK Rowling, wrote the books, making it so magically important that a different person destroys each Horcrux, I very much believe that she wrote them to be destroyed, in exactly the same order that they were made. However, wondering this question myself years ago, I reread the books, and I know for a fact that there is no conclusive proof in Cannon, that this is true. However, this is my personal belief.