I use photoshop CS4
The principle is similar to Tanya's fantastic tutorial. With your template open drag your photo or paper on to the template. Drag your paper/ photo in the layer window so that it is above the layer of the template you want to add it too. Hover the mouse pointer in the line between the template layer and your chosen paper or photo and hold down alt (I think it is ctrl on a mac), a little black arrow with 2 overlapping circles appears. Click the mouse pointer and your paper or photo will become the same shape as the layer beneath it.
You cna then use ctrl and t to transofrm the photo or paper as required. This is handy if you need to shrink a photo to fit the shape.
One last thing to remember is if the template layers are not preshadowed you need to shadow the template layers not your paper/ photo layers beause the shadows will not show.
Clear as mud isn't it
this was hard to explain without screen shots. If anyone is using the same program as me and needs help with this let me know and I will do a photo tutorial as well.