How to set pictures as iphone background at certain size?

I recently got an iphone 5c as a gift and i've been still trying to get the settings I want to it.
I wanted to set this picture as my lockscreen wallpaper, but when I try to set it, it's too big.

Does anyone have a solution on how to put the picture as the original size it is?

Added (1). Thank you so much Mandii!

Download Instasize and you can get the entire picture (:

Hope I helped! - Mandii