Yeah, my son (the Gamer) loaded Gimp onto his old computer after some updates before he gave it to me. I couldn't figure it out, and didn't see why it needed to be that fancy. I also tend to not need to crop my digital pictures, having learned to frame a picture pretty well with a 35mm film camera.
There are some work-arounds that some people do, like email themselves the picture and it comes back smaller and compressed and all. I think that's a poor & awful slow way to do it. Others use things like "FotoBucket" or some such, and I think it will reduce the file size for you, but you can also just post a link to the photo, which stays where it is, and is accessed by clicking on the link.
Speaking of messing with the file extensions (.exe, .jpg, .gif, etc.), long ago, I saved some pictures and after creating a title, I typed .jpeg. Guess what? Couldn't even open them on my own computer. Had to change the file extension and lose the "e". Then, all was well.
Steve