There are many places on the internet that houses a host of lovely template designers for you to choose from. Search and grab a template that you like and want to use, then open the template in your program.
I'm using a template by Dee'Sign Depot.
Below is a preview using a template by Leah at Gimptastic Tuts.
Open your first paper of choice and re-size to your needs. Add this above the chosen layer, like you would if adding layers.
This is what I came up with, using the first template: