https://support.nascarheat.com/customer/portal/articles/2953653-how-do-i-redeem-the-50-race-ticket-voucher-found-inside-my-nascar-heat-3-box-?b_id=17622
Go to nascarheatticket.com and enter your code. You will be asked to enter some basic info about yourself and the event you wish to attend. Soon after you will be contacted by a track representative who will help you get your tickets.