Hello Justine, and welcome to planDisney!
How exciting that you'll be visiting the
Disneyland Resort in just a few short weeks! In looking at the
Theme Park Reservation Availability calendar, it appears that your date is available, and it is not blocked out for a Tier 4 ticket.
Since you already have your tickets, please visit the
My Theme Park Reservations page, and then click "Book Theme Park Reservation". It will then prompt you to select your tickets, or link them again if they're not appearing. From there you should be able to select your date.
If you're looking to extend your trip outside of the Theme Parks, I recommend checking out the shopping and dining at the
Downtown Disney District, it's one of my favorite things to do on a non-park day.
I hope you have a magical visit!
Melissa