website designs

I was wondering if anyone new what dimensions Erin was using for the website. I am making the sketches but I was wanting to make them at the right size. I figured she was using the 1024 by whatever it is for the page size, but the I remember on her designs she also had that blue box inside of the yellow background, and I was not sure how big to make the box. If that makes since please let me know because I don't know how big to make anything