Ezra reads the Torah out loud. That must have been a thrilling morning. Then they realise it's Succor, so they set to work sacrificing animals, giving the meat away to the poor, and building shelters, which they haven't done since the days of Jeshua. A long time, in other words.
A few days later, it's time for another party. A costume party. They all dress up in sackcloth, fast, confess their sins, read the Torah, and confess their sins. Your average self-criticism session, in other words. Then they recap everything that has happened since Abraham.
The Israelites make a vow not to intermarry, to keep the sabbath and to tithe.