I have a panarama and wish to print out a 12x36 print exactly for a piece of gator board so I created a layout as shown (attached) but the whole image does not show. Is there a way to get this to fit. The file dimensions of the file is 20357x3697. Must be doing something wrong?

I must assume when you say the whole image doesn't show, you mean it has been cut off or "cropped.
If that is the case, then we have two choices.
Assuming that the missing piece is critical to the print, you can either turn off auto crop in which case you will get the entire image, but you may not get the filled out 12 x 36. That depends on the aspect ratio of the image.

The second choice and probably the better of the two for a pano, is to open the Page editor with the image in the queue, click on cropping tab, and using the 'hand' cursor, slide the image around to suite yourself. You can keep  what is critical and sacrifice a small portion to maintain theIn other words, 12 x 36 is a 3:1 aspect ratio. The image is close to 5:1.
So you either print it as a pano and you get full image size (crop off), or crop on, you get full print size.

Fred

It appears that it will not fill up a 12x36 and all the elements are needed I would rather not take part of the photo away so I guess I will need to do another pano.