Back up files

G'day,
I have backed up all my files on to a external hard drive. I use Windows Photo Gallery to file my photos.
I have been trying to find a photo that was backed up. I only want to retrieve it so that I can send it to somebody. Please could somebody tell me how I can do that. How can I find just my photos and look through them? If there is something about my problem on the forum please direct me to it please.
Thank you very much.
Cheers Perry