We use 'order' when dealing with a restaurant or some type of business. You order pictures from a professional photographer. If your friend took pictures of you and you'd like copies, you ask your friend for the photos.

You ASK FOR something, not 'ask' - the only thing you can 'ask' is a question! For example: I went into a cafe and I asked for a sandwich. I asked the waiter for a glass of water. 'Ask for' is more casual than 'order', and we tend to use it for face-to-face requests. If you choose something from a menu, we usually say 'order'. For example, a waiter brings you a menu and then says; 'Are you ready to order?' When you buy things online, arrange to have goods sent to your house, or arrange to have something made or delivered for you, we use 'order'. For example: Do you have these shoes in size 10? No, but we can order them for you. It takes two or three days. In your sentence about the photos, you would use 'order'.