Shrinking a banner image to fit in Blogger

As I suspected, some of the Blogger templates (such as Minima) allow you to shrink your banner image to fit the width of the main column. There is a box to check when you are editing the image in a template that supports that feature. ... Others require you to resize your image in another program, such as Photoshop. Unfortunately, there isn't a standard size for the photo to fit the column, but it's generally in the range of 600-750 pixels wide by 100-150 pixels high. So either choose a supportive template, or tinker with the image. Let me know if you need further assistance on this.