Hello! I'm not too sure what your job title/job scope is exactly whether you have to do layout the photos in an editorial or write the articles, or are you simply uploading articles and arranging a file of photos. But the thing about freelance/project-based jobs is that it can be tricky to determine how much to get paid for. It can either be per hour, like you suggested, or a lump sum. To give you some context, graphic designers who are still schooling charge around $10-$12/hour and I've also heard of fresh grads charging $100/day. The more experienced ones will charge more, based on how much experience they have. So if you are doing layout and writing then yes, $15 seems reasonable. (: However, what's more important when doing freelance work is that you draft up a contract to prevent the company from underpaying you or even fleeing payment. Try to be more detailed by coming up solutions for different scenarios, for instance charging them extra if they do last-minute changes or requesting 30% of the pay first, before you start on the project as a guarantee. All the best!