You're off to a great start with some of my favorite subject matter.

Rotate your future pictures so that they're upright--that makes it easier for us to appreciate your work.

If you're using Windows 10, the default Photos app can do the job with ctrl+R. 7 and 8.1 should be similar processes, just with Windows Photo Viewer instead of Photos.

If you're on Mac, open the picture in the Preview app and hit command+L or command+R.