In the Bible we find God's instructions on how His people should celebrate the Seasonal Feasts.  At the Last Supper, Jesus gave the commandment to do this in remembrance of Him and that He would join this meal again in His kingdom.  Throughout the Biblical year we see a progression taking place: The Spring-festivals point towards the first coming of Jesus while the Fall-festivals point towards His second coming.  The Feast of Tabernacles is the climax of the Fall celebrations, and according to the prophets, the nations will go up to Jerusalem to celebrate this Feast of the Lord.