How can I get photos into a locket necklace?

I bought my wife a nice necklace with heart shaped locket for Mother's Day and it can hold 2 photos. The problem is I have no idea how to get photos that small or into the locket. I know it is probably not that difficult but I have no idea how to do it. Please help me. Also, Happy Mother's Day to all of the mothers out there and thank you in advance for helping me out.