open your template, you should see all the layers on the right. if not you need to go into view (along the top) and select layers from the palettes toolbar.
now open up your other image, cut it
go back to your template, click on the bottom layer and go to edit(along the top) and paste as a new layer.
your image should be at the very bottm of all the layers.
you can unselect any layers you dont want to use by clicjking on the eye.it wont be visible.
always save your work as a psp file so you can change things if you need to.
save the finished cover as a jpg, but always keep the psp.
Sorry for my English, i'm from Leicester innit?