How did the pics on my pc get on my iphone5 iOS 8.1.3

I am the most technically challenged, no idea how to figure out what the **** I did kind of person. I'm not sure how I did it or how to fix my mess. I have been unable to backup my phone due to not enough space...so I moved all my photos to my computer, deleted games, emails, texts, etc. to make it work but it hasn't. Since then I have somehow loaded ALL of my photos that are located on my pc onto my iphone!!! How can I get them OFF my phone but keep them on my PC? AND how is it possible that I don't have enough storage?

Thanks for any help!!!! I'm ready to toss this thing in the trash!!!!