That is not a template as such. It is a basic indication of layout and size. Apart from that it is in Indexed mode, you need to change that to RGB Image -> Mode -> RGB otherwise all you get is black and white
You need to build it up layer by layer.
The background pattern
Various text layers. Note the large text is not a regular font, it has been coloured, has a drop shadow ...
The graph could be a selection filled with your pattern/gradient/image.. with that white grid on top.
Top left image, make your image to suit and add a border.
All just parts of using Gimp, but Gimp has a steep learning curve.
When it comes to a template that might be used many times over, much more complicated.
Layer groups for everything, but aimed at isolating the various parts for the user to fill in.
example:
http://i.imgur.com/ftCdUqU.jpg
and a gimp xcfgz of that to play with, 2 MB too big for here, so
http://www.mediafire.com/file/7x4ih3cl82...late.xcfgz