Okay kiddo, a long, long time ago in the year 1832 there was a meeting between some really important people from different countries. They all met in a place called Constantinople, which is now called Istanbul. The big reason they all got together was because they wanted to figure out how to make things better for a certain country called Greece.
You see, Greece wasn't doing too well at the time because they were trying to become their own country but they were having a lot of trouble. There were some people who lived there who wanted Greece to be their own country and other people who didn't want that to happen. So, the important people who met in Constantinople decided to make a treaty to try and settle things down.
A treaty is a special agreement between countries that helps to solve a problem. They talked about a lot of things in the treaty, like who would be in charge of Greece and what the new country would look like. They also talked about how the other countries around Greece would help out.
In the end, the treaty of Constantinople helped Greece become its own country. It also helped to keep the peace between the different countries around Greece. It was a very important moment in history that helped shape the world we live in today!