What was written on the rosetta stone? how did historians manage to decode the rosetta stone?

The Rosetta Stone is simply an announcement from then Pharaoh Ptolemy V describing the repealing of various taxes. In reality,what was said was not very important. What was really important was the two languages that were used to make the announcement, ancient Egyptian and ancent Greek.
By the time the year 1799 came around ancent Egyptian was a dead language, which was bad because many of the newly discovered cities, buildings and temples were covered in writings in an cent Egyptian, and there was no way tell what the Egyptians were up to. Nobody was able to translate. However, the Rosetta stone had the same announcement in both Egyptian (a dead language which nobody spoke) and Greek (a live language language which many people speak) Using the Rosetta stone as a guide, the French, then later the British, were able to figure out the an cent Egyptian language, and then bring a whole new light on the Egyptian people. It was a big breakthrough.