Here is my collection of the Striking Stripes Patterns for the new Blogger templates. You can download the patterns here. (There is an arrow on the lower right corner of every page to download the file).
1. Download your chosen pattern, or if you like, you can surely download as many you like.
2. To install the background pattern go to "Design" > "Customize" > "Templates"
3. Choose the template, I recommend "Simple"
4. Under the templates is "Background" > Click Background Image > Upload Image > pick the one you saved to your computer.
5. Alignment "up in middle" > "Tile" > and I recommend do not choose "Scroll with page"
6. Then you can choose the widths, layout and on "Advanced" you can choose the other colors. Try different options, it's fun. You can design your own unique look to your blog.
More instructions here.