This post explains how you can add a template variable to define a third party file host location. The file host defined here will be used to host all the custom images provided free with The Blogger Guide's various popular HOWTOs such as the three column and wider two column template conversions.
Go to Layout -> Edit HTML mode and add the variable as described below.
The template variable we add here is of type automatic. To incorporate it, simply add the code shown in red below, right to the end of your template's Variable declaration section. (Usually, the last variable on a default Blogger template is the endSide variable)
type="automatic" default="right" value="right">
<Variable name="imageHost" description="Image Host Location"
To learn more about Blogger template variables, read the article shown in Related Posts below.