Hi I went to register my 3ds online through the eshop and it said to put in the pin number to get 160 coins. Well, I didn't realize what the pin was and so I put in the wrong number. Now I didn't get the coins and I don't know how to go back and fix my mistake. Someone please help me,
I do not think that you can register your 3DS through the eShop, only through the Club Nintendo website. You should still be able to enter your PIN on this page (click here) to get the survey which will get your coins. You can link your 3DS to Club Nintendo through the eShop, however, which will allow games you download to be automatically registered. This page (click here) shows how to link your system.