iammcallum - don't know if this will work when the file is uploaded but I played around with my old software (Microsoft Digital Image Pro 10 that runs on Windows Vista

) and I have created a png (Portable Network Graphics) file. You will have seen from yansan's comment that when he created a png file it was too large to upload to rootschat. I too have cut out the footballer from yansan's jpg file and created a small png file. In my world the png files I call transparencies and I can take a copy of the png file and add it to a jpg file; save the jpg file and the png file becomes part of the jpg file.
I will upload your original Peter Johnstone file with a png and jpg file embedded into it. You should see the png file shows only the cut out figure wheras the jpg file shows the figure and the white background. I will then upload the very small png file . If this works you should be able to download/save the png file. When you add a png file to a jpg file it will nrmally have an outlie and the outline can be dragged by the corners to create a larger image to add into the jpg fie.
I will check out the png file after I have posted this comment + files to see if all is OK.