Need HELP viewing Gimp edited pics on iphoto

[imacnewb]

I am a complete mac newb.... i downloaded gimp on the open source website and was able to edit my photos to my liking, i absolutely love the software but my problem arises when i try to save the edited photos and view them on iphoto, they are simply not there. I open iphoto and the edited pictures do not appear. when i select them to upload them on to facebook for example it claims the picture is corrupt or in the wrong format. how do i save the picture in the correct format from gimp to view on iphoto, i have already tried simply tagging .jpg at the end when i try to save. any help or guidance would be much appreciated... thank you...