Sometimes a box of tickets (such as Fort Knox) don't sell out before the end of the night, and some people are holding tickets that might prove to be winners when the game is sold out and the seal is opened to determine winners.   If a player holding a potential winner does not come to play the net week when the ticket does sell out, we would be unable to continue on to the next box of that game because we wouldn't know if the jackpot had been won or not.   When you fill out  a carryover slip, you ensure your chance to win that game when it sells out the next week, whether you are present or not.   So you need to fill in your name, phone number, the name of the ticket (e.g., Fort Knox), the serial number on the side of the ticket (small black numbers along the side usually) and the ticket number that makes you a potential winner (usually a number ending in 13 that appears in one of the ticket windows).  You need to sign the slip, and sometimes you need to pick a winning number (depending on the game) that will be opened up on your behalf to determine if you are a jackpot winner.  Still confused?  Just ask any of the volunteers - we'll help you!!  :)