How to build a website: Problem with add a new page section.

I'm following through the how to build a website tasks on Treehouse. Everything has been going fine, but I've just got to the 'add a new page section' and I've hit my first problem. When copying the index.html file into the new about.html(new page) as told I get a completely different layout to the one in the example video. The whole layout is different.

The picture is much bigger, nothing is centered and I can't really work out why. I've copied the code exactly and the only thing I can think of is maybe because I've copied and pasted it might not be picking up the general css to go with the html on the new about.html page.

Any advice on how to solve this would be great. I'm really enjoying learning and I'm progressing well but I don't feel I can really carry on without solving this.

When looking over the code I don't think the newpage is picking up an id="wrapper" that I have in a <div> that links the css that stlyes and formats the page properly how can I solve this.