How do I upload my resume onto Internet applications from my iphone6?

When I attempt to upload my resume to the Internet, online job applications etc. it does not allow me to do so. It only gives me the option to take a picture or choose from my photo library. I have tried to screenshot my rresume and upload but it is not in PDF form so it denies the upload. How do I upload my resume or change my option to only upload from my photo library?