Visit USA.gov's Voting and Elections section to register to vote, become a poll worker, and learn about the election process.
http://www.usa.gov/Citizen/Topics/Voting.shtml
Each state has its own voter registration and absentee ballot deadline for the November 6 Presidential Election. Some states also offer early voting. Check out the 2012 election calendar to look up deadlines and early voting times in your state.
http://www.eac.gov/voter_resources/elec ... endar.aspx