I need help acheiving a sort of masking effect

I want to take a picture of a globe, and 'fill' each continent with a different picture, preventing anything in the picture that goes outside the continent from being seen. How would I go about doing that?

I would:

1. Make each different continent it's own layer, by either using the magic wand, or lasso tool. Then take that selection and press ctrl-shift-j (new layer via cut), and do this for each continent.

2. Take your picture that you want in the continent, and put it in the same graphic as the globe is in.

3. ctrl-click the layer with the desired continent, then click (without deselecting) the picture layer, and select the inverse and delete it. You may have to modify (select >>> modify >>> contract) your selection to make a little bit of the continent's edges visible to make it look better.

Man, I made myself clear enough.