Hi there Jessica,
Welcome to planDisney and thank you for your question! It looks like you'll be at the Disneyland Resort in just a few days - can you believe it?
Before I jump into your answer here, just a quick note that a couple of weeks ago the Disney Genie+ Service was renamed to
Lightning Lane Multi Pass to add clarity to the service. I'll be using that terminology in my answer below, but know that it's functionally the same thing!
Currently, there are two periods of time when you can add on the Lightning Lane Multi Pass service - at the time that you purchase your theme park tickets or after you scan your ticket for the first time to enter a park during your visit.
Since it sounds like you've already purchased your tickets, that means you'll want to add the Lightning Lane Multi Pass after you enter your first park on your trip here in a few days.
To do that, I'd recommend having the
Disneyland Resort mobile app up and ready. After you scan your tickets at the entry gate, you can navigate to the home page of the app and you'll see a green banner near the top of the screen that says "Lightning Lane Multi Pass." Tap the "Purchase" button and walk through the steps to finalize getting this added to your ticket and you'll immediately be able to use it!
To book your first Lightning Lane return time, I like to tap the "My Day >" button just beneath the green Lightning Lane Multi Pass banner then tap the "Tip Board" tab near the top left of the next screen. This list will show current wait times and you'll have the option to book a return time for attractions that offer a Lightning Lane.
Thanks again for your question, Jessica! I hope you enjoy your trip to the Happiest Place on Earth.
Have a Magical Day,
Greg