1). Eating no food. On Tuesday, you do not eat, only drink. You replace the time you would have eaten with prayer and hunger for God. Instead of talking about the election, you talk about the Lord. You can also use the time you would have eaten to go vote.
2). Fasting one meal. You might skip lunch or dinner. You replace the hour (preparation and clean-up including) with a longing for God. Write a note of encouragement or call someone battling cancer.
3). Forfeiting dessert. This is a good way to introduce children to fasting. They've been eating Halloween candy and they can do without on Tuesday - spending dessert time with reading the Bible, praying for our nation to turn to God. The king of Nineveh called for a fast, it included even the animals too (Jonah 3:6).
God relented from destroying Nineveh - He responded to their fast. We're asking God to respond to believer's throughout America, fasting for revival in our land.
Just like you make plans to vote on Tuesday, make plans to fast as well.