But here I'll do the work for you.
A simple Google search: http://www.pocket-lint.com/news/138312-how-to-access-android-n-nougat-easter-egg
Your first step, as already mentioned head to the settings menu, scroll all the way down until you reach "About Phone", tap that and find "Android version". If you press this option multiple times repeatedly, you'll get to a screen showing the Android N logo on your wallpaper.
Repeatedly tap the "N" a few times then press and hold on it and you should see a tiny cat emoji appear near the bottom of the screen.
Swipe down from the top of the screen to reveal your quick settings toggles and hit "edit". You should now see a cat face icon with the label, "???? Android Easter egg". Drag and drop this icon to to the main quick settings options and place it where you want it. Now, the fun can begin.
Hit your home button and then drag down the quick settings shade from the top of the screen again. This time you should see an "empty plate" option. Tap it and you'll see an overlay with four food choices: Bits, Fish, Chicken and Treat. Select one, then continue using your phone as normal, and wait.
Eventually, you'll get a notification telling you that a cat has snagged one of the treats. But it doesn't always work, which is kind of the point of the game. You have to keep trying, using different treats to bait a cat.
When it does work, you'll get a notification saying "a cat is here" with the number of the cat listed underneath. Tapping on the notification reveals a new screen with a cat icon which you tap once to rename, or long-press to reveal sharing options. You can save a full resolution version of the cat's picture to your device, or share it to all your social media accounts like every other crazy cat owner.