It is the same concept as horizontal scrolling. You can use a variable, like scrolly. You set the first sprites Y position to Scrolly+360 * 0. You use the amount 360 because the height of the screen is 360.
If you want to look at a project with scrolling, look at this one.
http://scratch.mit.edu/projects/Zelda123/83506
Tell me if you need any more help or clarifications.
Offline