Photoshop Tutorial
Making a Box with a Contoured Edge
Method:
1. Start with a transparent canvas. Draw a box or rectangle. Paint the box whichever color you like. I used white #FFFFFF.
2. Apply a Stroke style to the layer with the following settings:
3. Final image below.

4. Next we need to slice it into smaller sections for use in our webpage. For this tutorial, we'll save just three image slices like the ones below.
Top
Middle
Bottom

5. Save image slices for web, as transparent gifs. Place them in your website's image folder.