>>7273981>GimpWhen you do your thing I suggest you add a transparency channel on the chart template picture ("Add Alpha channel", pic related) and "hollow out" the picture slots (select them all with the magic brush/"fuzzy selection" while holding Shift, and press Delete or Ctrl+X).
Then you can add a layer ("New Layer" as in pic), click and move it under the first one, and paste your pictures on it while your original frame layer applies above them. That should spare you having to crop all the pics to the same proportions.
Also when you want to save something in a regular image format in Gimp you'll have to use "export" - the save options save as "gimp project" lossless-type files.