I appreciate this is a VERY novice question but I just want to check in regard to Tkinter Photoimage class, is it only GIF/PGM/PPM images that it can read from files and nothing else unless I download the Python Image Library.
If thats the case I now know exactly where I went wrong in the code I'm writing. IE: wrong file format
That sounds right.  There may be another format or two that native Tkinter supports, but it's very limited.  There's a more up-to-date version of PIL named Pillow that you might want to look into.  It doesn't seem like PIL is being actively maintained, last I looked.  If you want to work with JPEG for example, you need PIL (or Pillow).
Python Tkinter PhotoImage file formats supported?