I remember reading about this a few days ago, but it didn't apply to me until now. I want to add a new 3DS friend code. How do I do that?

Go to My Friend Codes, press "Edit" at the top, and then on the big list that comes up you'll find three Nintendo 3DS Code slots!

I'm not seeing 3 slots when I click on EDIT

Found it, had to click on 3DS icon at top of page. Thanks.

me being stupid where do u have to go on thia to get more friends codes

Go to the FC page, then click on EDIT, then click on the 3DS icon. a age opens up with the other slots available. Add your other Friend codes to the other slots.

where is the fc page

It's labeled "My Friend Codes", about halfway down the "My ACC" bar on the left.