How to claim your 10 free NES games for your Nintendo 3DS

Good evening, Mr Ambassador! Please, let me take your coat and that mighty fine hat of yours. Your dinner is being prepared as we speak. Please take a seat.

What's that? Yes, your ten free NES games came through today, sir. They're waiting on your Nintendo 3DS.

I beg your pardon, sir? You don't know how to download the free games? Well, that's quite alright - no need to feel embarrassed. It could happen to the best of us.

Let me explain to you how to grab those free NES games in an easy-to-understand step-by-step manner.

First off - are you actually eligible? You must have bought your Nintendo 3DS before August 11st, and visited the eShop at least once before. Forgot to boot up the eShop before the deadline? Don't worry - it's still possible to be an Ambassador.
Now that you're sure, let's get down to it. Boot up the eShop from your Nintendo 3DS main menu, and then scroll all the way to the left. See the option 'Settings/Other'? Stick your stylus on it. Go on, give it a press.
Your free games have been thrown into your account as if you've bought them just like any other game from the eShop - so you're going to find them in the same place as all your other games. Scroll down the list, and the third option should be 'Titles You've Downloaded', or 'Your Downloads' depending on your region. Press on this option.
Now, you should be able to see the past titles you've downloaded - and if you scroll a little down, you'll see all your new NES games, too. Now, simply press on any of these games and hit 'Redownload' to start downloading your games. Anything you download will appear on your 3DS main menu as normal. What's rather annoying is that for each separate title you'll have to repeat the last couple of steps, as it doesn't take you straight back to the games list. But, hey, this is Nintendo - when is anything easy?