You must REGISTER to vote if you want to take part in an election. If you are a US citizen, and will be the age of 18 by the time of the election in which you wish to vote, then it's pretty easy to register. Go to your local Circuit Clerk's office with your photo ID,and ask to register. Or you can simply download a form, print it, and fill it out and mail it to your local Circuit Clerk's office. You must register within 30 days of the election if you want to vote, but once you register you don't have to register again next time. You have to update your voter registration when you move, even if you stay in Mississippi.
Find out where your polling place is so you know where to go when it's time to vote. Think about transportation ahead of time. Find out what options are available in your area or make plans with a friend or family member to pick you up. Can't get to the polls? Vote absentee! Call your Circuit Clerk's office and have an absentee ballot mailed to you up to 45 days before the election. You can return it in person by noon three days before the election or by mail as long as your ballot is received by 5pm on voting day.