I don't know what program you are using. I use photshop elements and this is how I do it. it may be similar in other programs
open both the picture & the frame so they are both showing on the work area. Highlight the frame (just click on it), then go to image on your toolbar & click on mode. Change it to RGB. repeat this step for the picture as well. Both frame & picture have to be in RGB mode in order to be moved onto each other. once they are both in RGB mode and the picture is moved onto the frame or vice versa, you should see them both in your layer pallet. Then double click (in the layer pallet) the one that says background & rename it to layer 0. then you can tweak the frame & picture, meaning you can stretch it or make it smaller.
If you move the picture on top of the frame, and need to get it behind the frame, highlight the photo in the layer pallet, then click on layer on the toolbar, go down to arrange & click on move to back.
Hope this helped.
If you need any of my frames updated to 2007, just let me know which ones. I have a link to my frames in my signature