If you want to share a Checkout Page that you created with one of your friend's school that also use SPARK, share that Checkout Page with the Share Code. You can find the Share Code by going to:
Left Side Menu Bar > More Features > Checkout Pages
Under "Checkout Pages" page, scroll down to "General" section then click "Share Checkout Page" button.
After clicking, just provide the school you are sharing the Checkout Page with the Share Code that popped up.
You can place the share code to receive the Checkout Page by going up to the top selecting Enter Share Code and you will be able to enter the Code there to receive the Checkout Page.