My and my friend both want to be a photographer and I took a picture of her with her phone and she said she was gonna put it on instagram? It was a really good picture and I got mad because she was gonna take the credit for my picture? Do I have a right to be mad or should I get over myself..
Would it make you mad?
Would it make you mad?

I'd say it's normal, and I can see why you'd be defensive over something which you believe belongs to you. Your ego wants you to be praised. Your friend's ego wants to be praised as well, even for something which she didn't do. Either that or she just wanted to share the photo:/.
I'm sure your picture was bloody fantastic! Does that help?