Registration Field Problem???

So Hello Guys, I’m really bad with programming but I planned this site for years. Can someone help me with this;
So I was looking all over the internet to learn how to customize my registration fields. I found some plugins and tried them. But when I click register on my site my old fields are still there. So It looks really ugly. Can someone tell me step by step what to do? Thanks and my site is iDundle.com You can go there and try my registration to see it.