[romelled]

I'm trying to design a wallpaper customized for a site im working on. I want the header(top) content(middle) and footer to all have a different color and texture, similar to this http://colombiaholidays.com/. Is there a way to find out what the dimensions need to be for the Photoshop file so that it will cover the entire page and sections evenly?

[Andrea]

The dimensions will vary depending on content and the resolution a page is viewed with, so it'll never be the same for everybody. You can decide to create a page at the most common viewing resolution, but the content will still vary.

If you read up on how background images work, you'll find that they usually consist of a small image that repeats.

For a design like you mention, you'd create different divisions for your different sections and add a different background to each of them.