1. Download/Open GIMP. http://docs.solutiosoftware.com/recommended-downloads
2. Drag and Drop image file into GIMP:
3. Click 'Rotate':
4. Click 'Image' in the toolbar, then 'Transform', then 'Rotate (clockwise, counter-clockwise, 180) until it is oriented upright:
5. Click 'File', 'Export As', 'Export', 'Export':
6. The file is oriented correctly and ready to upload to the site.