Can someone tell me how to do this?

I want to take a photo of my friend from a FB page and put it in my photo gallery. I don't have a computer, just my smart phone.

Ultimately, what I am trying to do is get the photo of my friend onto a postage stamp on the PhotoStamp website so I can make postage stamps with her image on it. She starred in a short student film and the photo of her with her co-star is on FB.